Video camera printer apparatus and method of controlling same and apparatus and method for detecting print inhibit signal

ABSTRACT

Video signals are recorded in such a manner that prints having a high picture quality can be obtained while not interfering with playback of images in the form of a movie. A CCD is controlled in such a manner that exposure is performed at a shutter speed of 1/250 of a second, one time in exposures performed a plurality of times in succession, and at a shutter speed of 1/60 of a second at other times. The video signal outputted by the CCD is applied to a combining circuit via a CDS, AGC and signal processing circuit for an image sensing system. A PI signal generating circuit outputs a PI signal, which represents inhibition of printing, in the case where exposure is carried out at the shutter speed of 1/60 of a second, and the combining circuit superposes the PI signal upon the video signal, which has been obtained by exposure at the shutter speed of 1/60 of a second, in the vertical blanking interval of this video signal. The output of the combining circuit is applied to a recording playback head via a signal processing circuit for a recording system, whereby the output is recorded on a videotape.

This application is a continuation, of application Ser. No. 08/171,664filed on Dec. 22, 1993, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a video camera for recording a video signal,which is obtained by continuously photographing a subject, andreproducing the recording video signal in the form of still pictures ora movie; a printer apparatus which, using the video signal recorded bythe video camera, produces a printed picture of the image represented bythe video signal; and a method of controlling the video camera and theprinter apparatus. The invention further relates to a circuit which,when a print inhibit signal has been superposed upon the video signal,detects the print inhibit signal; and a method of detecting thesuperposed print inhibit signal.

2. Related Art:

In general, a video camera performs photography at a shutter speed of1/60 of a second. As a consequence, if it is attempted to reproduce astill picture of one frame of the moving subject from the movie videosignal, only a blurred picture of the moving image can be reproduced.

In order to obtain a sharp picture when reproducing a still picture of amoving subject, photography must be performed at a high shutter speed.Although a movie video camera capable of performing continuousphotography at a high shutter speed has been proposed, the impression ofcontinuity of the image from one frame to the next at the time of movieplayback is lacking and the motion of the subject in the reproducedimage appears unnatural. Thus, movie playback and still playback areincompatible.

Accordingly, consideration may be given to a method through which aplurality of successive frames are photographed at a shutter speed of1/60 of a second, and one frame among these frames is photographed at ahigh shutter speed (e.g., 1/250 of a second). In accordance with thismethod, high-speed photography is performed only once every severalframes so that there is no loss in the impression of continuity of thepicture.

Nevertheless, when photography is performed at a high shutter speed, thelevel of the video signal is lower than that of the video signal in acase where photography is performed at an ordinary shutter speed. Whenthe resulting image is printed, therefore, the printed picture may betoo dark. Furthermore, if the subject is illuminated by a fluorescentlamp, the image of the subject is affected by flickering of thefluorescent lamp.

Another problem encountered in an effort to make both still playback andmovie playback feasible is how to deal with a decline in the brightnessof the subject. When shutter speed is raised for the purpose ofobtaining a still reproduction, there is a decline in the level of thevideo signal obtained from a solid-state electronic image sensingdevice. If there is a decline in the brightness of the subject, there isa further decline in the level of the video signal. When a video signalof a low level is reproduced in the form of a still picture, asufficiently sharp picture is difficult to obtain.

On other hand, when a subject such as a person is photographed indoors,the subject is illuminated by the light from a lamp within the room.Since the luminance of light from a fluorescent lamp fluctuates at afrequency twice that of a commercial AC power supply, the reproducedimage may develop flicker when the video signal obtained by performingphotography under such illuminating light is reproduced. In other words,when a subject illuminated by a fluorescent lamp is photographed and theresulting image is played back in the form of a movie, there will becases in which the image flickers and appears unattractive.

SUMMARY OF THE INVENTION

An object of the present invention is to make it possible to obtain ablur-free, sharp reproduced still picture of a moving subject and toplay back a movie of the subject in such a manner that the movie givesan impression of continuity and possesses natural motion.

Another object of the present invention is to make it possible for avideo signal obtained by photography at a high shutter speed and a videosignal obtained by photography at an ordinary shutter speed of 1/60 of asecond to be distinguished from each other at reproduction.

A further object of the present invention is to make it possible for thelevel of a video signal obtained by photography at a high shutter speedand the level of a video signal obtained by photography at an ordinaryshutter speed to be made approximately equal.

Still another object of the present invention is to prevent, as much aspossible, a decline in the picture quality of a reproduced still pictureeven if there is a decline in brightness of the subject.

A further object of the present invention is to prevent the impressionof flickering of a reproduced image resulting from the effects offlicker.

A video camera according to a first aspect of the present inventioncomprises shutter implementing means capable of implementing a shutterhaving a high shutter speed and a shutter having an ordinary shutterspeed, shutter control means for controlling the shutter implementingmeans in such a manner that exposure at the high shutter speed isperformed one time periodically in photography performed a plurality oftimes in succession and exposure at the ordinary shutter speed isperformed at other times, photographic means for outputting a firstvideo signal representing an image of a subject when the subject isexposed at the ordinary shutter speed and a second video signalrepresenting the image of the subject when the subject is exposed at thehigh shutter speed, and recording means for recording the first andsecond video signals, which are obtained from the photographic means, ona recording medium.

The present invention further provides a method of controlling the videocamera.

The shutter implementing means includes an ordinary mechanical shutterand a so-called electronic shutter. In the electronic shutter, exposuretime (shutter speed) is defined by a length of time from the moment atwhich unnecessary electric charge is cleared from a solid-stateelectronic image sensing device to the moment at which a signal electriccharge is read out of the image sensing device.

The ordinary shutter speed refers to a shutter speed of 1/60 of a secondgenerally used in video cameras, and the high shutter speed refers to ashutter speed higher than the ordinary (1/60 of a second), such as ashutter speed of 1/125 or 1/250 of a second.

According to the present invention, photography at the high shutterspeed is performed one time periodically in photography performed aplurality of times in succession and photography at the ordinary shutterspeed is performed at other times.

Photography performed one time is processing for obtaining one field ofa video signal when a field mode is in effect and processing forobtaining one frame (two fields) of a video signal when a frame mode isin effect.

Accordingly, a sharp picture is obtained by reproducing a still picture(creating a printed picture or displaying an image on the screen of adisplay unit) using the video signal acquired by photography at the highshutter speed. Further, since photography at the high shutter speed iscarried out only one time in photography performed a plurality of timesin succession, no unusual impression is given when a movie isreproduced. The resulting moving has a natural appearance.

The inventor has learned from experience that photography at a highshutter speed (in the case of 1/250 of a second) should be performed onetime periodically in photography carried out 16 times in succession (inthe field mode). If photography at a high shutter speed is performed ata period on this order, an unnatural impression can be prevented atplayback in the form of a movie.

When an ordinary picture is taken, the maximum time interval forobtaining a desired picture without missing an opportunity for a goodshot is on the order of one second. Therefore, in consideration of thephotographer's wish not to lose a good photo opportunity, it would bedesirable for photography at the high shutter speed to be performed onetime periodically in photography carried out no more than 60 times insuccession in the field mode.

In an embodiment of the invention ideal for a case in which a printedpicture is obtained using a video signal obtained by photography at thehigh shutter speed, a print inhibit signal indicating that the imagerepresented by the first video signal is forbidden from being printed issuperposed in a vertical blanking interval related to the first videosignal, which is obtained by exposure at the ordinary shutter speed,from the video signals outputted by the photographic means.

Most generally the print inhibit signal would be inserted in thevertical blanking interval that immediately precedes the appearance ofthe first video signal.

In a printer apparatus provided with a video signal outputted by a videocamera according to the invention or a video signal read out of therecording medium recorded on by the video camera, the first video signalobtained by photography at the ordinary shutter speed and the secondvideo signal obtained by photography at the high shutter speed can bedistinguished from each other by detecting the print inhibit signal.Accordingly, the second video signal obtained by photography at the highshutter speed can be selected without fail so that a sharp printedpicture can be produced.

Furthermore, the print inhibit signal preferably is superposed between a17th horizontal synchronizing signal and an 18th horizontalsynchronizing signal in a vertical blanking interval of the first videosignal.

In general, various signals are superposed within the vertical blackinginterval. For example, an ITS (interface test signal) is inserted in abroadcast wave. The ITS is superposed between the 17th horizontalsynchronizing signal and 18th horizontal synchronizing signal as well.However, the signal superposed here is a test signal of a broadcaststation and therefore is unrelated to a playback device or picturereceiving device. The print inhibit signal thus can be superposedbetween the 17th horizontal synchronizing signal and 18th horizontalsynchronizing signal without causing problems. When loss ofsynchronization and the frequency characteristic are taken into account,it is preferred that the print inhibit signal be superposed in thelatter half of the vertical blanking interval.

In another embodiment of the invention, a warning signal indicating thatthe second video signal obtained by photography at the high shutterspeed will appear next is superposed in the vertical blanking intervalof the first video signal outputted by the photographic means byphotography at the ordinary shutter speed immediately preceding thephotography performed at the high shutter speed.

The fact that the second video signal resulting from photography at thehigh shutter speed will appear next is recognized by detection of thewarning signal. In a printer that prints a picture based upon the secondvideo signal, preparations for printing processing can be made inresponse to detection of the warning signal. Accordingly, theappropriate printing processing is possible even in a printer thatincludes a processing circuit having a slow processing speed.

In another preferred embodiment of the invention, an information signalrepresenting photographic information prevailing when the second videosignal is obtained and print information useful when printing a picturerepresented by the second video signal is superposed in a verticalblanking interval related to the second video signal, which is obtainedby photography under a high shutter speed, from the video signalsoutputted by the photographic means.

The information represented by the information signal is composed of thefact that use was made of a shutter speed other than 1/60 of a second,the shutter speed, F number, color temperature, date prevailing at thetime of photography, the title, whether the mode is the field or framemode, the magnetic recording format (8 mm normal; 8 mm high; VHS; S-VHS,etc.), the frame number, etc. These items of information are detected inthe printer apparatus, thereby facilitating the preparation of a printedpicture. Frame numbers are consecutive numbers assigned with regard tothe second video signal and are useful in searching for a specific stillpicture that has been photographed.

In a preferred embodiment of the invention, the video camera furthercomprises an amplifier circuit for amplifying the video signal outputtedby the photographic means, and gain control means for controlling thegain of the amplifier circuit in such a manner that the level of thesecond video signal obtained by exposure at the high shutter speed willbecome approximately equal to the level of the first video signalobtained by exposure at the ordinary shutter speed.

Since exposure time is shortened when photography is performed at thehigh shutter speed, the level of the video signal obtained declinesoverall and the reproduced image darkens. In accordance with thisembodiment, gain is controlled in such a manner that the average levelof the second video signal becomes approximately equal to the level ofthe first video signal. As a result, the reproduced image obtained has abrightness approximately equal to that of the reproduced image basedupon the first video signal obtained by photography at the ordinaryshutter speed. This eliminates any unnatural impression when an image isplayed back in the form of a movie.

A circuit for detecting a print inhibit signal according to a secondaspect of the present invention comprises reading means for readingvideo signals from a recording medium on which a first video signal anda second video signal have been recorded in such a manner that one frameof the second video signal appears one time in a prescribed plurality offrames of the first video signal, wherein the first video signalrepresents the image of a subject photographed at an ordinary shutterspeed and has a print inhibit signal, which represents inhibition ofprinting of an image represented by the video signal, superposed thereonin a vertical blanking interval, and the second video signal representsthe image of the subject photographed at a high shutter speed,superposed-signal detecting means for detecting and outputting thesuperposed signal, which has been superposed in the vertical blankinginterval, from the video signal read by the reading means,superposed-signal output verifying means for verifying whether thesuperposed signal detected and outputted by the superposed-signaldetecting means ceases periodically, and a print-inhibit signal outputcircuit for outputting, as the print inhibit signal, the superposedsignal detected by the superposed-signal detecting means when thesuperposed-signal output verifying means has verified that output of thesuperposed signal ceases periodically.

The circuit for detecting the print inhibit signal is provided in theprinter apparatus. According to the invention, the print inhibit signalsuperposed upon the video signal using the above-described video cameracan be detected. Accordingly, it can be determined that a video signalfor which the print inhibit signal has not been detected has beenobtained by photography at the high shutter speed, and a printed picturehaving a sharp image can be obtained in the printer apparatus basedsolely upon a video signal obtained by photography performed at a highshutter speed. In detection of the print inhibit signal, whether thesignal superposed in the vertical blanking interval of the video signalstops periodically is verified. As a result, a print inhibit signalsuperposed in association with the first video signal that appears at afixed period can be detected upon being distinguished from the aforesaidITS or the like that appears in all vertical blanking intervals.

The circuit for detecting a print inhibit signal according to thepresent invention is suitable also for use in a display unit. In suchcase, only a sharp still picture based upon the second video signal willbe displayed on the display unit.

A printer apparatus according to a third aspect of the present inventioncomprises print-inhibit signal detecting means for detecting a printinhibit signal, which has been superposed in a vertical blankinginterval, from a video signal wherein a second video signal, whichrepresents an image of a subject photographed at a high shutter speed,has been inserted in a prescribed plurality of frames of a first videosignal representing the image of the subject photographed at an ordinaryshutter speed and having a print inhibit signal, which representsinhibition of printing of an image represented by the video signal,superposed thereon in a vertical blanking interval, memory control meansfor performing control, based upon the print inhibit signal outputted bythe print-inhibit signal detecting means, in such a manner that a videosignal not containing the print inhibit signal in its vertical blankinginterval is stored in memory means, and printing means for reading thevideo signal stored in the memory means out of the memory means basedupon control performed by the memory control means, and printing animage represented by the video signal that has been read out.

In accordance with the invention, there is provided an apparatus forprinting an image represented by a video signal stored on a recordingmedium by a video camera. The printer apparatus is supplied with thevideo signal read from the recording medium. It is of course possible toprovide the printer apparatus with means for reading the video signalfrom the recording medium.

In either case, the print inhibit signal superposed upon the videosignal in the vertical blanking interval thereof is detected, adesignated part of the second video signal not accompanied by the printinhibit signal is stored in the memory means and is used as image datafor creating a printed picture. Thus, since a printed picture is createdbased solely upon the second video signal obtained by photography at thehigh shutter speed, a sharp still picture is obtained at all times.

A print inhibit signal is not inserted in a video signal obtained in theconventional video camera. Accordingly, even if the video signalobtained with the conventional video camera is applied to the printerapparatus of the present invention, the printer apparatus will perform aprinting operation. In other words, the printer apparatus according tothe present invention is applicable to video signals produced by boththe video camera of the present invention and video cameras according tothe prior art.

In a preferred embodiment of the printer apparatus according to thepresent invention, the apparatus is further provided with warning-signaldetecting means for detecting whether a warning signal, which indicatesthat the second video signal will appear, has been superposed in avertical blanking interval of the first video signal immediatelypreceding the appearance of the second video signal, andpreparation-signal output means responsive to detection of the warningsignal by the warning-signal detecting means for outputting apreparation signal to the memory control means so as to prepare control,executed by the memory control means, for storage of the video signal inthe memory means.

Since preparation for storage of the video signal in the memory meanscan thus be carried out, a video signal obtained by photography at thehigh shutter speed can be stored reliably and printed even in a printerapparatus having a control circuit exhibiting a slow operating speed.

In another embodiment, the printer apparatus is further provided withprinting-condition signal detecting means for detecting an informationsignal, which is superposed in the vertical blanking interval of thesecond video signal, representing photographic information prevailingwhen the second video signal is obtained or print information usefulwhen printing a picture represented by the second video signal.

The information detected may be displayed on the display unit of theprinter apparatus whenever required in order to assist the user.Alternatively, the information may be used in order to control theprinting operation performed by the printer apparatus in order toproduce a printed picture.

A video camera according to a fourth aspect of the present inventioncomprises shutter implementing means for periodically repeating exposureperformed at a high shutter speed one time in photography of aprescribed plurality of successive frames and exposure performed at anordinary shutter speed at other times, photographic means for outputtinga first video signal when exposure is performed at the ordinary shutterspeed and a second video signal when exposure is performed at the highshutter speed, an amplifier circuit for amplifying the first and secondvideo signals, which are outputted by the photographic means, at twodifferent amplification factors in such a manner that the level of thefirst video signal will become approximately equal to the level of thesecond video signal, first integrating means for integrating one frameof the first video signal and outputting a first integrated value, asecond integrating means for integrating one frame of second first videosignal and outputting a second integrated value, subtracting means forproducing a difference signal representing the difference between thefirst and second integrated values, and adjusting means for adjusting atleast one of the two different amplification factors of the amplifiercircuit, based upon the difference obtained from the subtracting means,in such a manner that the difference is eliminated.

A method of controlling a video camera according to a fourth aspect ofthe present invention comprises a step of periodically repeatingexposure performed at a high shutter speed one time in photography of aprescribed plurality of successive frames and exposure performed at anordinary shutter speed at other times, a step of obtaining a first videosignal when exposure is performed at the ordinary shutter speed and asecond video signal when exposure is performed at the high shutterspeed, a step of applying amplification processing to the first andsecond video signals, which are outputted by the photographic means, attwo different amplification factors, in such a manner that the level ofthe first video signal will become approximately equal to the level ofthe second video signal, a step of obtaining a first integrated value byintegrating one frame of the first video signal, a step of obtaining asecond integrated value by integrating one frame of the second videosignal, a step of calculating a difference between the first and secondintegrated values, and a step of adjusting at least one of the twodifferent amplification factors in the amplification processing basedupon the calculated difference in such a manner that the difference iseliminated.

In accordance with the present invention, the difference is calculatedbetween a first integrated value of the video signal of a first imageexposed at an ordinary shutter speed and an integrated value of a videosignal of a second image, which is adjacent to the first image, exposedat a suitable shutter speed. On the basis of the difference calculated,at least one of two amplification factors for amplification processingof the first and second video signals is adjusted so as to eliminate thedifference calculated.

When the difference between the first and second integrated valuesvanishes, the average level of the first video signal and the averagelevel of the second video signal become equal. Regardless of any changein characteristics such as those of the circuit for amplifying thelevels of the video signals, the average level of the first video signaland the average level of the second video signal become equal and animage printed based upon the second video signal is brightened.

It is preferred that exposure at the high shutter speed be performed onetime in photography of a plurality of successive frames the number ofwhich is a multiple of six.

When a fluorescent lamp is lit by an alternating current having arepetition frequency of 50 Hz, the light-emission period is 1/100 of asecond. When the fluorescent lamp is lit by an alternating currenthaving a repetition frequency of 60 Hz, the light-emission period is1/120 of a second. When photography is repeated at a shutter speedfaster than 1/100 of a second, the amount of integration of the videosignal is different each time photography is performed and flicker isthe result.

On the other hand, the period of photography in a video camera is 1/60of a second. Therefore, if photography is carried out every threefields, the amount of integration of the video signal each timephotography is performed should be the same, and flicker should beprevented, even when photography is performed under illumination by afluorescent lamp driven by an alternating current having a frequency of50 or 60 Hz. However, the amount of light produced when a fluorescentlamp is discharged from right to left differs from that produced whenthe fluorescent lamp is discharged from left to right. Consequently, ifphotography is performed every six fields, the amount of integration ofthe video signal each time photography is performed will be the same andthe effects of flicker will diminish.

Exposure at the high shutter speed is performed one time in a pluralityof times the number of which is a multiple of six. As a result, theamount of integration of the video signal each time high-speedphotography is performed will be the same and the effects of flicker canbe reduced.

A video camera according to a fifth aspect of the present inventioncomprises shutter implementing means for periodically repeating exposureperformed at a first high shutter speed one time in a prescribedplurality of successive frames and exposure performed at an ordinaryshutter speed at other-times, photographic means for outputting a firstvideo signal when exposure is performed at the ordinary shutter speedand a second video signal when exposure is performed at the first highshutter speed, an amplifier circuit for amplifying the first and secondvideo signals, which are outputted by the photographic means, atmutually different amplification factors in such a manner that theaverage level of the second video signal will become approximately equalto the average level of the first video signal, first sensing means forsensing that the average level of the first video signal has fallenbelow a first threshold value, and first shutter control meansresponsive to sensing by the first sensing means for controlling theshutter implementing means in such a manner that the first high shutterspeed will become a second shutter speed lower than the first highshutter speed but higher than the ordinary shutter speed.

The present invention further provides a method of controlling theabove-described video camera.

According to the fifth aspect of the present invention, the first highshutter speed changes to a second high shutter speed lower than thefirst high shutter speed but higher than the ordinary shutter speed whenthe average level of the first video signal, which is obtained whenphotography is performed at the ordinary shutter speed, falls below thefirst threshold value.

When the brightness of the subject declines and the average level of thefirst video signal falls below the first threshold value, the first highshutter speed changes to a second high shutter speed lower than thefirst high shutter speed and exposure time is lengthened as a result.When the average level of the second video signal also rises and thesecond video signal is reproduced, a sharp image is obtained. Further,since the second shutter speed is higher than the ordinary shutterspeed, this is suited to still playback as before and a blur-freereproduced picture is obtained.

Since photography at the first or second shutter speed is carried outonly one time (e.g., one time in 16 fields or more) in a plurality ofsuccessive times, no unusual impression is given and a naturalappearance is obtained even in movie playback.

It is preferred that photography at the high shutter speed be carriedout one time in 60 frames or less, by way of example, so that photoopportunities will not be lost.

In an embodiment of the fifth aspect of the invention, a secondthreshold value lower than the first threshold value is established.When the average level of the first video signal falls below the secondthreshold value, the second high shutter speed is made a third shutterspeed lower than the second high shutter speed but higher than theordinary shutter speed.

By thus providing a second threshold value, a high shutter speedsuitable for the purpose of obtaining a sharp reproduced image can beadjusted over a plurality of steps in conformity with the brightness ofthe subject. As a result, it is possible to accommodate various changesin the brightness of the subject so that a sharp reproduced image may beobtained.

The third shutter speed may be set to the ordinary shutter speed.

In another embodiment of the fifth aspect of the invention, a thirdthreshold value lower than the second threshold value is set. When theaverage level of the first video signal falls below the third thresholdvalue, a frame to be photographed at the high shutter speed isphotographed at the ordinary shutter speed. Since the brightness of thesubject is fairly low, photography of the frame for the purpose of stillplayback is no longer carried out.

A video camera according to a sixth aspect of the present inventioncomprises shutter implementing means for periodically repeating exposureperformed at a high shutter speed one time in a prescribed plurality ofsuccessive frames and exposure performed at an ordinary shutter speed atother times, photographic means for outputting a first video signal whenexposure is performed at the ordinary shutter speed and a second videosignal when exposure is performed at the high shutter speed, anamplifier circuit for amplifying the first and second video signals,which are outputted by the photographic means, at mutually differentamplification factors in such a manner that the average level of thesecond video signal will become approximately equal to the average levelof the first video signal, brightness measuring means for measuringbrightness of a subject, and shutter control means responsive to achange in brightness measured by the brightness measuring means forcontrolling the shutter implementing means in such a manner that thehigh shutter speed is changed continuously from a prescribed highershutter speed to the ordinary shutter speed.

The invention further provides a method of controlling theabove-described video camera.

According to the sixth aspect of the present invention, the brightnessof the subject is measured and the shutter speed is changed continuouslyfrom a prescribed high shutter speed to the ordinary shutter speed independence upon a change in subject brightness. Therefore, even if thebrightness of the subject declines, a second video signal for stillreproduction resulting from photography at a comparatively large amountof exposure is obtained. A sharp still picture that is free of blurringand possesses suitable brightness may thus be obtained at all times.

The brightness of the subject can be found by measuring the averagelevel of the first video signal obtained by exposing the subject at theordinary shutter speed, just as in the case of the fifth aspect of theinvention.

A video camera according to a seventh aspect of the present inventioncomprises shutter implementing means for periodically repeating exposureperformed at a high shutter speed one time in a prescribed plurality ofsuccessive frames and exposure performed at an ordinary shutter speed atother times, photographic means for outputting a first video signal whenexposure is performed at the ordinary shutter speed and a second videosignal when exposure is performed at the high shutter speed, anamplifier circuit for amplifying the first and second video signals,which are outputted by the photographic means, at mutually differentamplification factors in such a manner that the average level of thesecond video signal will become approximately equal to the average levelof the first video signal, brightness measuring means for measuringbrightness of a subject, and shutter control means, which in response tothe fact that brightness measured by the brightness measuring means isbelow a prescribed level, is for controlling the shutter implementingmeans in such a manner that the high shutter speed will become theordinary shutter speed.

The invention further provides a method of controlling theabove-described video camera.

According to the seventh aspect of the present invention, the brightnessof the subject is measured and the high shutter speed is set to theordinary shutter speed when the measured brightness is lower than aprescribed level.

When the brightness of the subject is low and a suitable brightnesscannot be obtained, exposure is performed at the ordinary shutter speedrather than at the high shutter speed. As a result, the level of thevideo signal also rises and a movie image possessing suitable brightnessis obtained. Further, since photography at the high shutter speed forstill playback is not carried out, a video signal not necessarilyappropriate for still playback will not be produced. This makes itpossible to prevent erroneous still playback.

In the embodiment of the fifth through seventh inventions, opening andclosing of a diaphragm is controlled in dependence upon a change insubject brightness in such a manner that the average level of the firstvideo signal and the average level of the second video signal are bothmaintained at prescribed levels, and the high shutter speed is sloweddown only when the diaphragm is opened fully.

The amount of exposure can be adjusted by the diaphragm and the level ofthe video signal can be raised even if the brightness of the subjectdeclines. Since the shutter speed is slowed down when the diaphragm isopened, exposure at the comparatively high shutter speed can bemaintained until the diaphragm is opened. Accordingly, it is possible toaccommodate even a comparatively fast-moving subject.

A video camera according to an eighth aspect of the present inventioncomprises shutter implementing means for periodically repeating exposureperformed at a first high shutter speed one time in a prescribedplurality of successive frames and exposure performed at an ordinaryshutter speed at other times, a diaphragm for limiting amount ofincident light representing the image of a subject; photographic meansfor outputting a first video signal when exposure is performed at theordinary shutter speed and a second video signal when exposure isperformed at the first high shutter speed, an amplifier circuit foramplifying the first and second video signals, which are outputted bythe photographic means, at mutually different amplification factors insuch a manner that the average level of the second video signal willbecome approximately equal to the average level of the first videosignal, brightness measuring means for measuring brightness of thesubject, diaphragm control means for controlling opening and closing ofthe diaphragm, in dependence upon a change in the brightness measured bythe brightness measuring means, in such a manner that the average levelof the first video signal and the average level of the second videosignal will both be maintained at prescribed levels, and gain controlmeans which, in response to the diaphragm being opened fully on thebasis of control by the diaphragm control means, controls theamplification factors of the amplifier circuit in such a manner that theaverage level of the first video signal and the average level of thesecond video signal will both be maintained at the prescribed levels.

According to the eighth aspect of the invention, the opening and closingof the diaphragm is controlled in response to a change in the brightnessof the subject in such a manner that the average levels of the first andsecond video signals will be maintained at prescribed levels. After thediaphragm has been opened, the gain of the amplifier circuit is raised.Accordingly, the average levels of the first and second video signalsare maintained at the prescribed levels at all times so that a brightreproduced image is obtained. Since the gain of the amplifier circuit israised after the diaphragm has been opened, the gain of the amplifiercircuit does not rise so much until the diaphragm is opened. As aresult, the reproduced image obtained has a favorable S/N ratio and isbright.

In an embodiment of the eighth aspect of the invention, the video camerafurther comprises first sensing means for sensing that the average levelof the first video signal is below a first threshold value, and firstshutter control means responsive to sensing by the first sensing meansfor controlling the shutter implementing means in such a manner that thefirst high shutter speed will become a second high shutter speed lowerthan the first high shutter speed but higher than the ordinary shutterspeed.

Thus, even if gain is raised to the limit of capability of the amplifiercircuit, the level of the second video signal, whose level becomesparticularly low, can be raised even in a case where the average levelof the video signal does not reach the prescribed level. As a result, abright and sharp reproduced image is obtained.

In another embodiment of the eighth aspect of the invention, the videocamera further comprises print-inhibit signal superposing means forsuperposing a print inhibit signal, which represents inhibition ofprinting of an image represented by the video signal, in a verticalblanking interval associated with the first video signal among the videosignals outputted by the photographic means, and means which, inresponse to the fact that the high shutter speed has become the ordinaryshutter speed, is for controlling the print-inhibit signal superposingmeans in such a manner that the print inhibit signal will alsosuperposed also in a vertical blanking interval associated with thesecond video signal.

The first video signal unsuited to still reproduction and the secondvideo signal suited to still reproduction can be distinguished from eachother by detecting the print inhibit signal at the time of playback. Asa result, still reproduction is possible using the second video signalsuited to still reproduction.

When the level of the first video signal falls below a second thresholdvalue, the print inhibit signal is superposed also in the verticalblanking interval associated with the second video signal. Accordingly,when the high shutter speed becomes comparatively low and is now longersuitable for still reproduction, still reproduction can be inhibited bydetecting the print inhibit signal.

A video camera according to a ninth aspect of the present inventioncomprises shutter implementing means for periodically repeating exposureperformed at a first high shutter speed one time in a prescribedplurality of successive frames and exposure performed at an ordinaryshutter speed at other times, photographic means for outputting a firstvideo signal when exposure is performed at the ordinary shutter speedand a second video signal when exposure is performed at the first highshutter speed, an amplifier circuit for amplifying the first and secondvideo signals, which are outputted by the photographic means, atmutually different amplification factors in such a manner that theaverage level of the second video signal will become approximately equalto the average level of the first video signal, flicker discriminatingmeans for discriminating whether the difference between average levelsof video signals representing two successive frames in the video signalsamplified by the amplifier circuit is greater than a prescribed valueand detecting that the difference is greater than the threshold value,thereby determining that flicker is caused in the video signal byilluminating light, and control means, which is responsive to thedetermination made by the flicker discriminating means that flicker iscaused in the video signal by illuminating light, for controlling theshutter implementing means in such a manner that the first high shutterspeed and the ordinary shutter speed in the shutter implementing meanswill become an identical shutter speed that corresponds to a positivewhole-number multiple of the period of an AC power supply of a lightsource generating the illuminating light, and controlling the amplifiercircuit in such a manner that the amplification factors of the amplifiercircuit become identical with regard to the first and second videosignals.

When a subject is illuminated by light that flickers, as in the mannerof light from a fluorescent lamp, the brightness of the subjectfluctuates so that there is a difference in brightness from one screento the next. In other words, a difference develops between the averagelevels of two fields (or two frames) of a video signal representing animage of two successive frames.

Accordingly, by comparing the levels of the video signals representingan image of two successive frames, it is possible to determine whetherthe reproduced image is being affected by flickering illuminating light.

The frequency of flicker of an illuminating device such as a fluorescentlamp corresponds to the AC frequency of the commercial power supply. Ifit is assumed that a shutter speed (e.g., 1/100 of a second) equivalentto a whole-number multiple of the period (e.g., 1/50 of a second) of thecommercial power supply, then the average level of the video signalrepresenting the image of each frame will be constant and flickering ofthe reproduced image can be prevented.

According to the invention, and by virtue of the above-describedtechnique, it is determined whether the subject is being influenced byflickering ascribable to light from a fluorescent lamp or the like. Whenit is judged that the subject is being affected by flicker, exposure iscarried out at an identical shutter speed corresponding to awhole-number multiple of the period of the AC power supply. This meansthat the reproduced image will not flicker.

In an embodiment of the ninth aspect of the invention, the shutter speedcorresponding to the positive whole-number multiple of the frequency ofthe AC power supply is a value lower than that of the high shutter speedbut higher than that of the ordinary shutter speed.

This makes it possible to obtain a video signal capable of reproducing ablur-free, sharp still picture that is not affected by flicker.

In another embodiment of the ninth aspect of the invention, the videocamera further comprises brightness measuring means for measuringbrightness of the subject, and shutter control means, which isresponsive to the fact that brightness of the subject measured by thebrightness measuring means is below a prescribed level, for controllingthe shutter implementing means in such a manner that the high shutterspeed will become the ordinary shutter speed.

Since the brightness of the subject diminishes so that a video signalfor still playback is not obtained, the video camera operates so as toprovide only a video signal for a movie.

Other features and advantages of the present invention will be apparentfrom the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating the electrical configuration of avideo camera according to a first embodiment of the present invention;

FIG. 2 is a block diagram illustrating the construction of a PI signalgenerating circuit;

FIGS. 3a and 3b illustrate recording formats of an interval photographymode, in which FIG. 3a shows a case for field recording and FIG. 3b acase for frame recording;

FIG. 4a illustrates a video signal recorded by the interval photographymode, and FIG. 4b illustrates, in enlarged form, the vertical blankinginterval of the video signal shown in FIG.4a;

FIG. 5a illustrates an example of a PI signal, FIG. 5b an example of aPI signal and a PIL signal, FIG. 5c an example of an information signaland FIG. 5d an example of an ITS;

FIG. 6 is a block diagram illustrating the electrical configuration of aprinter apparatus according to a second embodiment of the presentinvention;

FIG. 7 is a time chart showing input and output signals of each block ofthe printer apparatus;

FIG. 8 is a block diagram showing the electrical configuration of a PIsignal separating circuit;

FIGS. 9a and 9b are time charts showing input and output signals of eachblock of the PI signal separating circuit, in which FIG. 9a shows a casein which a video signal that includes a PI signal enters the PI signalseparating circuit and FIG. 9b shows a case in which broadcast wavesenter the PI signal separating circuit;

FIG. 10 is a block diagram illustrating the electrical configuration ofa video camera according to a third embodiment of the present invention;

FIG. 11 is a time chart showing the operation of the video cameradepicted in FIG. 10;

FIG. 12 is a block diagram showing the construction of a PI signalgenerating circuit;

FIG. 13 is a waveform diagram showing an example of a PI signalsuperposed upon a video signal;

FIG. 14 is a time chart for describing the prevention of flicker;

FIG. 15 is a block diagram illustrating the electrical configuration ofa video camera according to a fourth embodiment of the presentinvention;

FIG. 16 is a graph illustrating the relationship among subjectbrightness, the average level of a video signal, F number and gain;

FIG. 17 is a circuit diagram showing an example of the construction ofan averaging circuit and flicker detecting circuit; an

FIG. 18 is a time chart showing input and output signals of each circuitillustrated in FIG. 17.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

FIGS. 1 through 5 illustrate a first embodiment of a video cameraaccording to the present invention.

FIG. 1 is a block diagram illustrating the electrical configuration ofthe video camera, and FIG. 2 is a block diagram illustrating thespecific construction of a PI signal (print inhibit signal) generatingcircuit included in the video camera.

FIGS. 3a and 3b illustrate recording formats in the video cameraillustrated in FIG. 1, in which FIG. 3a shows a case for field recordingand FIG. 3b a case for frame recording. FIGS. 4a and 4b illustratesignals recorded in the video camera shown in FIG. 1, in which FIG. 4ashows a plurality of fields of a recording signal and FIG. 4billustrates, in enlarged form, a vertical blanking interval in therecording signal of FIG. 4a. FIGS. 5a through 5d illustrate signalssuperposed in the vertical blanking interval of a video signal, in whichFIG. 5a shows a PI signal that inhibits printing, FIG. 5b a PIL signal(which indicates that the next field of the video signal is capable ofbeing printed) superposed on the last field of a plurality of successivefields in which PI signals are inserted, and a PI signal, FIG. 5c aninformation signal representing various information related tophotography and printing, and FIG. 5d an example of an ITS (describedlater).

The video camera includes a mode setting button 16 which makes itpossible to set a movie photography mode, an interval photography modeand a sports photography mode. The movie photography mode is theordinary photography mode in which a subject is photographedcontinuously at a shutter speed of 1/60 of a second at all times. Theinterval photography mode is a mode in which a subject is photographedcontinuously over a prescribed plurality of fields at a shutter speed of1/60 of a second, with photography being performed periodically at ahigh shutter speed (e.g., 1/250 of a second) in just one field (or oneframe) among these plurality of fields. This sequence is performed inrepeated fashion. The sports photography mode is a mode in which asubject is photographed continuously at a high shutter speed at alltimes.

A signal representing the mode set by the mode setting button 16 isapplied to the system controller 15. On the basis of the entered modesetting signal, the system controller 15 outputs a shutter controlsignal to control a shutter control circuit 12, whereby photographyconforming to each mode is carried out. In the description that follows,a case will be discussed in which the interval photography mode has beenset by the mode setting switch 16.

A light image representing the image of a subject formed by an imagepick-up lens 2 is acted upon by a diaphragm 3 controlled by a diaphragmcontrol circuit 11, whereby the image of the subject is formed on a CCD4.

In the interval photography mode, an electronic shutter operation isperformed in the CCD 4 under the control of the shutter control circuit12 in such a manner that the sequence comprising the continuous exposureover a prescribed plurality of times at the ordinary shutter speed of1/60 of a second and the single exposure at the high shutter speed of1/250 of a second is repeated. This operation is illustrated in FIGS. 3aand 3b, in which the hatched portions indicate fields in whichphotography is performed at the high shutter speed and the otherportions indicate fields in which photography is performed at theordinary shutter speed. FIG. 3a depicts field recording and FIG. 3bframe recording. In the case of frame recording, photography is carriedout at the high shutter speed with regard to two successive fields inphotography performed a plurality of times. High shutter-speedphotography one time or two successive times is performed in 16 fields.It goes without saying that readout of the video signal from the CCD 4is executed every 1/60 of second, just as in an ordinary video camera,without relation to the value of shutter speed.

As will be described later, a PI signal is superposed on the videosignal obtained by photography at the ordinary shutter speed, this videosignal being among those outputted by the CCD 4. The manner in which thePI signal is inserted also is shown in FIGS. 3a and 3b.

The video signal outputted by the CCD 4 is applied to an AGC (automaticgain control circuit) 6 and automatic exposure detecting circuit 14 viaa CDS (correlated double-sampling circuit) 5.

The automatic exposure detecting circuit 14 extracts a luminance signalfrom the entering video signal, integrates the extracted luminancesignal over a fixed time interval and applies the integrated signal tothe system controller 15. On the basis of the integrated luminancesignal provided by the automatic exposure detecting circuit 14, thesystem controller 15 outputs a diaphragm control signal to control thediaphragm in such a manner that the amount of exposure is renderedsuitable at all times in the photography of ordinary shutter speed.

The automatic gain control circuit 6, whose amplification factor ischanged over based upon a gain control signal from the system controller15, is capable of amplifying the entering video signal at whichever oftwo amplification factors has been selected. The automatic gain controlcircuit 6 raises the amplification factor for the video signal obtainedby photography at the high shutter speed so as to make it larger thanthe amplification factor for the video signal obtained by photography atthe ordinary shutter speed, thereby performing an adjustment in such amanner that the average levels of the two kinds of video signals (thevideo signals outputted by the AGC circuit 6) will become approximatelyequal.

The video signals whose levels have thus been adjusted by the automaticgain control circuit 6 are applied to a signal processing circuit 7 forthe image sensing system. The signal processing circuit 7 executessignal processing for generating R, G, B signals, adjusting the colorbalance of these signals, performing a gamma correction and producing aluminance signal and color-difference signals. Video signals resultingfrom this processing are applied to a combining circuit 8.

The video camera further includes a PI signal generating circuit 20. Thelatter is provided with a horizontal synchronizing signal HD, a verticalsynchronizing signal VD and a clock signal CK from an SSG (synchronizingsignal generating circuit ) 13, and with data representing informationrelating to photography and information relating to printing, etc., fromthe system controller 15. On the basis of these input signals and data,the PI signal generating circuit 20 generates the PI signal, a PILsignal indicating that a PI signal is the last among PI signals whichcontinue over a plurality of fields, information signals representingphotographic information and printing information, and interval timingpulses that decide the period of photography at the high shutter speed.The interval timing pulses are applied to the system controller 15 andthe PI signal, PIL signal and information signals are applied to thecombining circuit 8.

The combining circuit 8 superposes the PI signal, PIL signal andinformation signals outputted by the PI signal generating circuit 20 onthe video signals (at least the luminance signal) outputted by thesignal processing circuit 7 for the image sensing system.

An example of the PI signal is shown in FIG. 5a, an example of the PILsignal is shown in FIG. 5b, and an example of an information signal isshown in FIG. 5c. Further, an example of an ITS inserted in a broadcastwave is shown in FIG. 5d. (The ITS, or "interface test signal", is aspecial signal inserted in the field blanking interval of a televisionsignal.)

The PI signal illustrated in FIG. 5a is inserted in an initial intervalIT₁ of a vertical blanking interval associated with the video signalobtained by performing photography at the ordinary shutter speed of 1/60of a second. The PI signal is not inserted in a vertical blankinginterval associated with the video signal obtained by performingphotography at the high shutter speed.

The PI signal and PIL signal shown in FIG. 5b are inserted in theinitial interval IT₁ of the vertical blanking interval associated withthe video signal obtained by photography performed at the shutter speedof 1/60 of a second one signal before the video signal obtained byphotography at the high shutter speed. The combination of the PI signaland PIL signal indicates that printing will be inhibited because thevideo signal is one obtained by performing photography at the shutterspeed of 1/60 of a second, and gives warning of the fact that the videosignal, which has been obtained by performing photography at the highshutter speed at which printing is possible, will arrive. Since the PILsignal is merely for the purpose of giving warning, it need not alwaysbe attached to the PI signal.

The information signal of FIG. 5c is inserted in the interval other thanthe initial interval IT₁ of the blanking interval associated with thevideo signal obtained by photography performed at the high shutterspeed. The information signal includes ID data (an information ID)indicating that the signal is an information signal. This is inserted inan interval IT₂ that is for identifying the information signal. Theinformation represented by the information signal is composed of thefact that use was made of a shutter speed other than 1/60 of a second,the shutter speed, F number, color temperature, date prevailing at thetime of photography, the title, whether the mode is the field or framemode, the magnetic recording format (8 mm normal; 8 mm high; VHS; S-VHS,etc.), the frame number, etc. The ID data contained in this informationis always inserted when any item of information has been inserted. Withregard to the other information contained, one or a plurality of theseitems of information may be inserted as desired. Of course, in a casewhere such information is unnecessary in the printer apparatus, theinformation signal need not be inserted. Further, the information signalmay be inserted not in the vertical blanking interval associated withthe video signal obtained by performing photography at the high shutterspeed but in a vertical blanking interval associated with the videosignal obtained by performing photography at the ordinary shutter speedbefore or after the above-mentioned vertical blanking interval.

The ITS of FIG. 5d is inserted over the entirety of the verticalblanking interval.

The vertical blanking interval associated with the video signalpreferably is a vertical blanking interval that appears immediatelybefore this video signal.

Thus, the PI signal, PIL signal and information signal are superposed onthe video signal in a form staggered with respect to time. By contrast,a portion of the ITS signal partially overlaps the PI signal, PIL signaland information signal in terms of time.

The PI signal, PIL signal and printing condition signal (informationsignal) are outputted by the PI signal generating circuit 20 at a timeat which they will be superposed on the video signal between the 17thhorizontal synchronizing signal and 18th horizontal synchronizing signalin the vertical blanking interval, as shown in FIG. 4b.

The video signal outputted by the combining circuit 8 is applied to asignal processing circuit 9 for the recording system. The video signalis subjected to recording processing such as pre-emphasis and frequencymodulation processing by the processing circuit 9, after which theprocessed video signal is recorded on a video tape 18 by arecording/playback head 10.

The video camera shown in FIG. 1 can perform reproduction processing aswell and includes a signal processing circuit 17 for the playbacksystem.

In the playback mode, the video signal that has been recorded on thevideo tape 18 is read by a recording/playback head 10 and applied to asignal processing circuit 17 for the playback system. The signalprocessing circuit 17 delivers this signal to the exterior of theapparatus as a playback signal obtained by applying demodulating andde-emphasis processing to the signal that enters the circuit 17. Forexample, the resulting signal is applied to a printer apparatus,described later.

FIG. 2 is a block diagram showing the construction of part of the PIsignal generating circuit 20.

The PI signal generating circuit 20 includes a counter 21, an encoder 22and a register 23. The clock signal CK outputted by the SSG 13 isapplied to the counter 21 and encoder 22, and the horizontalsynchronizing signal HD and vertical synchronizing signal VD are appliedto the counter 21. Data relating to photography and printing outputtedby the system controller 15 is applied to the encoder 22 via theregister 23.

The counter 21 includes a first counter for counting the horizontalsynchronizing signal HD and a second counter for counting the verticalsynchronizing signal VD. The value 17 is preset in the first counter.The second counter counts a value indicating the period (e.g., 16fields) at which time photography is to be performed at the high shutterspeed, counts a value that is smaller than this period by one, andrepeats this counting operation at the above-mentioned period. When theabove-mentioned period has been counted, the second counter generates afirst signal and applies it to the encoder 22. When a value one smallerthan this period has been counted, the second counter generates a secondsignal and applies it to the encoder 22.

On the basis of entry of the vertical synchronizing signal VD, the firstcounter of the counter 21 counts the horizontal synchronizing signal HDthat enters from the beginning of the vertical blanking interval,detects the 17th horizontal synchronizing signal HD of the verticalblanking interval and applies a detection signal to the encoder 22. Whenthe detection signal indicative of detection of the horizontalsynchronizing signal enters, the encoder 22 generates the PI signal(FIG. 5a) if both the first signal and second signal are not enteringfrom the second counter. Further, when the detection signal indicativeof detection of the 17th horizontal synchronizing signal enters, theencoder 22 generates the PI signal and the PIL signal (FIG. 5b) if thesecond signal is entering from the second counter. Furthermore, when thedetection signal indicative of detection of the 17th horizontalsynchronizing signal enters, the encoder 22 encodes, by a prescribedmethod, the data provided by the register 23 to generate the informationsignal (FIG. 5c) if the first signal is entering from the secondcounter. The PI signal, PIL signal and information signal are applied tothe combining circuit 8.

Further, in response to the first signal provided by the second counter,the encoder 22 outputs an interval timing pulse. The interval timingpulse is applied to the system controller 15. The latter responds toentry of the interval timing pulse by commanding the shutter controlcircuit 12 to operate at the high shutter speed in the next field.

The photographic period based upon the high shutter speed preferably hasa range of from 16 to 60 fields. The reason for this is that ifphotography at the high shutter speed is performed one time in 16fields, an unusual appearance will not occur when images are played backin the form of a movie. In case of photography at the high shutter speedperformed one time in 60 fields, i.e., one time in one second, it ispossible to avoid a situation in which a photo opportunity is lost.

Second Embodiment

FIGS. 6 to 9b illustrate an embodiment of a printer apparatus and PIsignal separating (detecting) circuit according to the presentinvention.

FIG. 6 is a block diagram illustrating the electrical configuration ofthe printer apparatus, FIG. 7 is a time chart showing input and outputsignals of each circuit in the printer apparatus, FIG. 8 is a blockdiagram showing the electrical configuration of the PI signal separatingcircuit included in the printer apparatus of FIG. 6, and FIGS. 9a and 9bare time charts showing input and output signals of each circuit blockof the PI signal separating circuit.

As shown in FIG. 6, a playback video signal obtained by being read froma video tape is applied to a synchronous separating circuit 31, a PIsignal separating circuit 40 and a frame memory 32 in a printerapparatus.

The playback signal outputted by the video camera shown in FIG. 1 may befed directly into the printer apparatus, a playback unit may be providedwithin the printer apparatus and a playback video signal read from avideo tape loaded in the playback unit may be used, or use may be madeof a playback video signal outputted by a separately provided playbackunit.

The horizontal video signal HD, vertical synchronizing signal VD andclock signal CK are separated from the playback video signal by thesynchronous separating circuit 31, and the separated horizontal videosignal HD, vertical synchronizing signal VD and clock signal CK areapplied to the PI signal separating circuit 40, a system controller 35,etc.

The PI signal separating circuit 40 extracts the PI signal, PIL signaland information signal, which have been superposed upon the verticalblanking interval of the entering playback video signal, from this videosignal, applies these extracted signals to the system controller 35 and,when the PI signal has not been extracted, generates a PIN signalindicative of this fact and applies the PIN signal to the systemcontroller 35.

When printing is performed, the playback video signal (this may be allframes of the playback video signal or solely the video signal obtainedby photography at the high shutter speed) is applied to a monitordisplay unit (not shown) so that the image represented by the videosignal may be shown on the monitor. While viewing images displayed onthe monitor, the user finds the image desired to be printed. When thedesired image has been found, the user presses a print button to apply afreeze pulse FP to the system controller 35.

The system controller 35 includes a flip-flop (not shown) set by theleading edge of the vertical synchronizing signal and reset by detectionof the PI signal. If the PI signal is not detected, the output FF of theflip-flop is held at the H level. A freeze timing pulse FT is producedin the system controller 35. The pulse FT rises a fixed length of timeafter the vertical synchronizing signal VD rises (the pulse rise is alsolater than the timing at which the flip-flop is reset by the PI signal).

The system controller 35 takes the logical product of the flip-flopoutput FF, the freeze timing pulse FT and the freeze pulse FP, and theresult of this operation is applied to a memory controller 36 as acontroller control signal (see FIG. 7).

When the controller control signal is applied to the memory controller36, the latter applies a memory write signal to a frame memory 32 sothat the playback video signal that enters immediately thereafter willbe written in the frame memory 32. Thus, after the print button 37 ispressed, the first appearing video signal obtained by photography at thehigh shutter speed is stored in the frame memory 32.

The memory controller 36 outputs the memory write signal only when theinitial controller control signal has been applied thereto. Thenceforth,even when the controller control signal is applied, the memorycontroller 36 will not issue the memory write signal until printingoperation ends or until the freeze pulse FP is again provided bypressing the print button 37 again.

Though an A/D converter circuit is not shown in FIG. 6, it goes withoutsaying that if the playback video signal is an analog signal, the videosignal will be stored in the frame memory 32 after being converted intodigital data. When the video signal obtained by photography at the highshutter speed is in the field mode, one field of image data is writtenin the frame memory 32. When this video signal is in the frame mode, twosuccessive fields of the image data are written in the memory 32.

The image data stored temporarily in the frame memory 32 is applied to aprinter-signal processing circuit 33, which subjects this data to signalprocessing in accordance with control based upon the print-conditioncontrol signal and applies the resulting signal to a print engine 34.The signal outputted by the print engine 34 is applied to a thermal head(not shown) so that the image represented by the video signal stored inthe frame memory 32 will be printed to obtain a printed picture.

An arrangement may be adopted in which the system controller 35 outputsthe controller control signal based upon the PIN signal outputted by thePI signal separating circuit 40. In such case it will be unnecessary toprovide the system controller 35 with the above-mentioned flip-flop.

Further, in response to the PIL signal provided by the PI signalseparating circuit 40, the system controller 35 is capable of applying aprint-preparation command to the memory controller 36, printer-signalprocessing circuit 33 and print engine 34, etc. The PIL signal appearsone field earlier than the video signal obtained by the photography atthe high shutter speed. Consequently, the memory controller 36,printer-signal processing circuit 33 and print engine 34, after beingprovided with the PIL signal, are capable of being provided with apreparation time of at least one field interval with regard to storageof the video signal, which has been obtained by photography at the highshutter speed, in the memory, signal processing of this signal and theoperation for printing the signal. Accordingly, it is possible toutilize circuitry having a slow speed of response. With regard to thesystem controller 35 also, the PIN signal enters (or the PI signal doesnot enter) upon passage of one field interval following entry of the PILsignal. As a result, the preparation interval up to output of the memorywrite signal and print command, etc., can be secured based upon the PINsignal (or cessation of the PI signal).

The data signal applied to the system controller 35 from the PI signalseparating circuit 40 is used in various applications. The data signalrepresents information related to photography and printing, as set forthabove. In this information, the frame number, for example, is applied tothe display unit and is displayed along with the image. While viewingthis display, the user is capable of pressing the print button 37 whenthe image having the designated frame number appears. Alternatively, ifa frame number has been entered from a keyboard (not shown) in advance,control can be performed in such a manner that only the video signalassociated with this frame number is stored in the frame memory 32.Thus, a video signal desired to be printed can be specified by a varietyof such methods using a frame number.

Field/frame data indicates whether a video signal is a field-mode videosignal or a frame-mode video signal. Therefore, the writing of imagedata in the frame memory 32 can be controlled based upon this data.

Shutter speed, F number, color temperature, date and title, etc., areuseful in creating a printed picture. The print-condition control signalis created from this data and is applied to the printer-signalprocessing circuit 33 and print engine 34. As a result, it is possibleto create a printed picture of excellent quality at all times, and thedate, title, etc., can be entered on the printed picture wheneverdesired.

In the embodiment set forth above, only a specific video signaldesignated for printing is written in the frame memory 32. However, itis possible to adopt an arrangement in which all video signals obtainedby photography at the high shutter speed are written successively in theframe memory 32 (a video signal written in the memory 32 previously iserased by writing in a new video signal), with writing of video signalsin the memory 32 being halted upon entry of a freeze pulse indicatingthat printing is to be carried out. Thus, one frame of image datawritten in the frame memory 32 last remains in the frame memory 32. Inthis case, display of the image can be performed based upon the datathat has been stored in the frame memory 32.

Processing for detecting the PI signal, PIL signal and print-conditiondata and processing for generating the PIN signal will be described withreference to FIG. 8 and FIGS. 9a, 9b. FIG. 9a is a time chart for a casein which a playback signal of a video signal obtained in the intervalphotography mode is fed into the PI signal separating circuit 40, andFIG. 9b is a time chart for a case in which a video signal of anordinary broadcast wave is fed into the PI signal separating circuit 40.

The ITS is inserted in the vertical blanking interval of the ordinarybroadcast wave. The ITS is inserted in the vertical blanking intervalsof all fields and is not periodically absent as in the manner of the PIsignal. Even if a broadcast wave in which the ITS has been inserted inthe vertical blanking interval enters, the PI signal separating circuit40 distinguishes the ITS signal and is capable of detecting the PIsignal correctly.

The PI signal separating circuit 40 is provided with the playback videosignal and with the horizontal synchronizing signal HD, verticalsynchronizing signal VD and clock signal CK extracted by the synchronousseparating circuit 31.

The playback video signal fed into the PI signal separating circuit 40is applied to a binarizing circuit 41, whereby the signal is convertedinto binary data. The binary data is applied to a decoder 43. Thethreshold level of the binarizing circuit 41 is set at a level at whichthe PI signal, PIL signal and information signal can be binarized.

Among the signals that enter the PI signal separating circuit 40, thevertical synchronizing signal VD and horizontal synchronizing signal HDare applied to a counter 42 and the clock signal CK is applied to thedecoder 43.

The counter 42 counts the horizontal synchronizing signal HD thatfollows the start of the vertical blanking interval and outputs adetection signal to the decoder 43 in response to detecting the 17thhorizontal synchronizing signal.

Upon entry of this detection signal, the decoder 43 accepts the binarysignal provided by the binarizing circuit 41 and distinguishes betweenthe PI signal (and PIL signal) and the information signal. The decoder43 provides a first monostable multivibrator 44 and an AND gate 46 withdata (any one of the PI signal, PIL signal or ITS) that enters from thebinarizing circuit 41 in the initial interval IT₁ of one horizontalscanning interval in which the PI signal and PIL signal have beensuperposed. Further, the decoder 43 judges whether the initial intervalIT₁ has data or not and compares data in the interval IT₂, which is foridentifying the information signal, with predetermined ID data. If theresult of the comparison is that the data in the interval IT₂ foridentifying the information signal agrees with the ID data, the signalis judged to be the information signal. When this is the case, the readdata is applied to a register 48. If the data is the ITS or the like andnot an information signal, then this data is not applied to the register48.

The data that enters the register 48 is fed into the system controller35 from the PI signal separating circuit 40 and is used in variousapplications, as set forth above.

The first monostable multivibrator 44 has a time constant on the orderof 1.1 V (where V is one vertical scanning interval).

The first monostable multivibrator 44 makes a transition to the unstablestate (at which its output attains the H level) in response to an inputpulse signal and then reverts to the stable state (at which its outputattains the L level) upon elapse of a period of time equivalent to 1.1V. In a case where the signal that enters the PI signal separatingcircuit 40 is a video signal obtained in the interval photography mode,the PI signal (and PIL signal) outputted by the decoder 43 is absentonce or twice at a fixed period. When the first monostable multivibrator44 makes a transition to the unstable state in response to the PI signal(and PIL signal) and the PI signal enters again before elapse of thetime 1.1 V, the output of the multivibrator 44 continues to be held atthe H level. However, the output falls to the L level if the PI signaldoes not enter over a period of time equal to or greater than 1.1 V.When the video signal obtained in the interval photography mode hasentered, the output of the first monostable multivibrator 44 falls tothe L level at a fixed period.

By contrast, when a broadcast wave has entered, the signal component ofITS always enters the first monostable multivibrator 44 before the timeperiod of 1.1 V elapses. Accordingly, the first monostable multivibrator44 attains the unstable state and is maintained at the H level at alltimes.

The output of the first monostable multivibrator 44 enters a secondmonostable multivibrator 45. The latter makes a transition to theunstable state (at which is output attains the H level) in response tothe trailing edge of the input pulse signal and reverts to the stablestate (at which its output falls to the L level) when time equivalent to65 V elapses.

In the case of the video signal obtained in the interval photographymode, the output of the first monostable multivibrator 44 assumes the Llevel at a fixed period. Accordingly, the second monostablemultivibrator 45 assumes the unstable state and its output is held atthe H level.

When the broadcast wave has entered the PI signal separating circuit 40,the output of the first monostable multivibrator 44 is at the H level atall times. Accordingly, since the input pulse signal does not decaywithin the time period of 65 V, the stable state is attained at alltimes and the L level is maintained in the monostable multivibrator 45.

The output of the second monostable multivibrator 45 enters the AND gate46.

When the video signal obtained in the interval photography mode hasentered the PI signal separating circuit 40, the output of the secondmonostable multivibrator 45 will always be at the H level and thereforethe PI signal (and PIL signal) outputted by the decoder 43 will passthrough the AND gate 46. As a result, the PI signal (and PIL signal)obtained in the interval photography mode can be separated by the PIsignal separating circuit 40.

When the broadcast wave has entered the PI signal separating circuit 40,the output of the second monostable multivibrator 45 will always be atthe L level and therefore the signal component of the ITS outputted bythe decoder 43 will not pass through the AND gate 46. Accordingly, thePI signal (and PIL signal) obtained in the interval photography mode andthe broadcast wave can be distinguished by the PI signal separatingcircuit 40 and it is possible to output only the PI signal (and PILsignal). Further, the PI signal outputted by the AND gate 46 is appliedalso to a counter 47. The latter is preset to a value representing theperiod at which the video signal obtained by photography at the highshutter speed appears (the aforesaid value expresses the period in theform of the number of vertical scanning intervals). The value of thecount in the counter 47 is decremented whenever the PI signal enters,and the counter 47 issues the PIN signal when the value of the countbecomes zero. The value representing the aforementioned period is thenpreset in the counter 47 again.

Third Embodiment

FIG. 10, which is for describing a third embodiment of the invention, isa block diagram illustrating the electrical configuration of a videocamera according to this embodiment. FIG. 11 is a time chart showingoperation when photography is performed using the video camera depictedin FIG. 10.

FIG. 12 iS a block diagram showing the specific construction of a PIsignal generating circuit included in the video camera.

FIG. 4a, which illustrates the signal recorded in the video camera, iseffective unchanged in this embodiment as well. FIG. 13 illustrates thePI signal that inhibits printing and corresponds to FIG. 5a. The videocamera performs photography of a subject continuously over a prescribedplurality of fields (the number of which preferably is a multiple ofsix, such as 12 fields, 18 fields, etc.) at a shutter speed of 1/60 of asecond, with photography being performed periodically at a high shutterspeed (e.g., 1/250 of a second) in just one field (or one frame) amongthese plurality of fields.

Since photography is performed at the high shutter speed one timeperiodically in the number of which is a multiple of six, the reproducedimage is prevented from being affected by the flickering of afluorescent lamp or the like. The reasons for this will be describedlater.

A light image representing the image of a subject formed by the imagepick-up lens 2 is acted upon by the diaphragm 3, whereby the image ofthe subject is formed on the CCD 4.

An electronic shutter operation is performed in the CCD 4 under thecontrol of the shutter control circuit 12 in such a manner that thesequence comprising the continuous exposure over a prescribed pluralityof times at the ordinary shutter speed of 1/60 of a second and thesingle exposure at the high shutter speed of 1/250 of a second isrepeated. This operation is illustrated at the top of FIG. 11, where thehatched portions indicate fields in which photography is performed atthe high shutter speed and the other portions indicate fields in whichphotography is performed at the ordinary shutter speed. Photography isperformed at the high shutter speed one time in 18 fields. It goeswithout saying that readout of the video signal from the CCD 4 isexecuted every 1/60 of second, just as in an ordinary video camera,without relation to the value of shutter speed.

As will be described later, a PI signal is superposed on the videosignal obtained by photography at the ordinary shutter speed, this videosignal being among those outputted by the CCD 4.

The video signal outputted by the CCD 4 is applied to the automatic gaincontrol circuit 6 via the CDS (correlated double-sampling circuit) 5.

The automatic gain control circuit 6, whose amplification factor ischanged based upon a gain control signal from a system controller 120,is capable of amplifying the entering video signal at whichever of twoamplification factors has been selected. The automatic gain controlcircuit 6 raises the amplification factor that is for the purpose ofamplifying the video signal obtained by photography at he high shutterspeed so as to make it larger than the amplification factor that is forthe purpose of amplifying the video signal obtained by photography atthe ordinary shutter speed, thereby performing an adjustment in such amanner that the average levels of the two video signals will becomeapproximately equal. For example, if the amplification factor prevailingat the time of the ordinary shutter speed (1/60 of a second) is A, thena gain control signal that will make the amplification factor prevailingwhen the shutter speed is 1/250 of a second equal to A.(250/60) will beapplied to the circuit 6.

The video signals whose levels have thus been adjusted by the automaticgain control circuit 6 are applied to the signal processing circuit 7for the image sensing system. The signal processing circuit 7 subjectsthe video signals to signal processing for adjusting the color balanceof these signals and performing a gamma correction, and generates aluminance signal and color-difference signals. The signals obtained bythis processing are applied to the combining circuit 8.

The video camera further includes a PI signal generating circuit 20A.The latter is provided with a horizontal synchronizing signal HD, avertical synchronizing signal VD and a clock signal CK from the SSG(synchronizing signal generating circuit ) 13. On the basis of theseinput signals, the PI signal generating circuit 20A generates the PIsignal as well as interval timing pulses that decide the period ofphotography at the high shutter speed. The interval timing pulses areapplied to the system controller 120 and the PI signal is applied to thecombining circuit 8.

The combining circuit 8 superposes the PI signal outputted by the PIsignal generating circuit 20A on the video signals (at least theluminance signal) outputted by the signal processing circuit 7 for theimage sensing system.

An example of the PI signal is shown in FIG. 13.

The PI signal illustrated in FIG. 13 is inserted in an initial intervalIT of a vertical blanking interval associated with the video signalobtained by performing photography at the ordinary shutter speed of 1/60of a second. The PI signal is not inserted in a vertical blankinginterval associated with the video signal obtained by performingphotography at the high shutter speed.

The vertical blanking interval associated with the video signalpreferably is a vertical blanking signal that appears immediately aheadof this video signal.

The PI signal is outputted by the PI signal generating circuit 20A at atiming at which it will be superposed upon the video signal between the17th and 18th horizontal synchronizing signals in the vertical blankinginterval, as shown in FIG. 4b.

The video signal outputted by the combining circuit 8 is applied to thesignal processing circuit 9 for the recording system. The video signalis subjected to recording processing such as pre-emphasis and frequencymodulation processing by the processing circuit 9, after which theprocessed video signal is recorded on the video tape 18 by therecording/playback head 10.

The video camera shown in FIG. 10 can perform reproduction processing aswell and includes the signal processing circuit 17 for the playbacksystem. This circuit is identical with that described earlier inconnection with the first embodiment.

The luminance signal produced in the processing circuit 7 for the imagesensing system is applied to a first integrating circuit 121 or a secondintegrating circuit 122 via a changeover switch 125. The firstintegrating circuit 121 and the second integrating circuit 122, whichare reset respectively by reset signals RST1 and RST2 provided by thesystem controller 120, integrate the equivalent of one image portion ofthe luminance signal. The video camera illustrated in FIG. 10 integratesone field of the luminance signal owing to field photography. However,if the video camera performs frame photography, one frame of theluminance signal will be integrated.

In the field in which the luminance signal obtained by photography atthe high shutter speed is being outputted by the signal processingcircuit 7 for the image sensing system, the changeover switch 125 ischanged over so as to be connected to the side of an a terminal. In thenext field (a field in which the luminance signal obtained byphotography at the ordinary shutter speed is outputted), the changeoverswitch 125 is changed over so as to be connected to the side of an bterminal. In other fields the changeover switch 125 is not connected toeither the a or the b terminal. One field of the luminance signalobtained by photography at the high shutter speed is integrated by thefirst integrating circuit 121. One field of the luminance signalobtained by photography at the ordinary shutter speed, which luminancesignal is that of a frame contiguous in time to a frame represented bythe luminance signal integrated by the first integrating circuit 121, isintegrated by the second integrating circuit 122.

A first integrated value resulting from integration performed by thefirst integrating circuit 121 and a second integrated value resultingfrom integration performed by the second integrating circuit 122 areapplied to a difference calculating circuit 123. The latter is a circuitfor calculating difference data between the first and second integratedvalues applied thereto. The difference data calculated in the differencecalculating circuit 123 is applied to a holding circuit 124, which holdsthe data temporarily.

The difference data held in the holding circuit 124 is read out of thiscircuit in response to a switch circuit 126 being turned on. The switchcircuit 126 is turned on during the field in which the video signalobtained by photography at the high shutter speed enters the AGC 6.

In response to the switch circuit 126 turning on, the difference data isoutputted by the holding circuit 124 and is added, as a gain correctionsignal (e.g., a voltage signal) to the gain control signal delivered bythe system controller 120, and the resulting signal is applied to theAGC 6 as a control signal. The magnification factor of the AGC 6 ischanged in conformity with the control signal (the voltage signal)resulting from the addition operation.

The characteristic of the AGC 6 changes slightly owing to aging andvariations in temperature. As a consequence, merely changing over theamplification factor by the gain control signal provided by the systemcontroller 120 does not necessarily mean that equivalence will always beestablished between the amplified level of the video signal obtained byphotography at the high shutter speed and the amplified level of thevideo signal obtained by photography at the ordinary shutter speed. Withthe video camera illustrated in FIG. 10, the gain control signal appliedto the AGC 6 is corrected in such a manner that the difference betweenone field of the integrated value of the video signal obtained byphotography at the high shutter speed and one field of the integratedvalue of the video signal obtained by photography at the ordinaryshutter speed, namely the integrated values of the video signalsrepresenting images contiguous in terms of time, will be eliminated,i.e., in such a manner that these integrated values of the video signalswill be equalized. Accordingly, irrespective of any change in thecharacteristic of the AGC 6, the level of the video signal obtained byphotography at the high shutter speed and the level of the video signalobtained by photography at the ordinary shutter speed will become equal.

FIG. 12 is a block diagram illustrating the construction of part of thePI signal generating circuit 20A. This circuit is obtained byeliminating the register 23 from the circuit depicted in FIG. 2.

More specifically, the PI signal generating circuit 20A includes thecounter 21 and the encoder 22. The clock signal CK outputted by the SSG13 is applied to the counter 21 and encoder 22, and the horizontalsynchronizing signal HD and vertical synchronizing signal VD are appliedto the counter 21.

The counter 21 includes a first counter for counting the horizontalsynchronizing signal HD and a second counter for counting the verticalsynchronizing signal VD. The value 17 is preset in the first counter.The second counter counts a value indicating the period (e.g., 18fields) at which photography is to be performed at the high shutterspeed and repeats this counting operation at the above-mentioned period.When the above-mentioned period has been counted, the second countergenerates a first signal and applies it to the encoder 22.

On the basis of entry of the vertical synchronizing signal VD, the firstcounter of the counter 21 counts the horizontal synchronizing signal HDthat enters from the beginning of the vertical blanking interval,detects the 17th horizontal synchronizing signal HD of the verticalblanking interval and applies a detection signal to the encoder 22. Whenthe detection signal indicative of detection of the horizontalsynchronizing signal enters, the encoder 22 generates the PI signal(FIG. 13) if the first signal is not entering from the second counter.The PI signal is applied to the combining circuit 8.

Further, in response to the first signal provided by the second counter,the encoder 22 outputs an interval timing pulse. The interval timingpulse is applied to the system controller 120. The latter responds toentry of the interval timing pulse by commanding the shutter controlcircuit 12 to operate at the high shutter speed in the next fieldinterval.

As set forth above, performing photography at the high shutter speed onetime periodically over a number of fields which is a multiple of sixmakes it possible to prevent a reproduced image from being influenced byflickering as caused by a fluorescent lamp. The principle according towhich this is performed will now be described.

FIG. 14 illustrates a vertical synchronizing signal VD, light emissionin a case where a fluorescent lamp is lit by an alternating currenthaving a repetition frequency of 50 Hz, light emission in a case where afluorescent lamp is lit by an alternating current having a repetitionfrequency of 60 Hz, and integrated values of light incident upon acamera when the fluorescent lamp is lit at 50 Hz or 60 Hz in photographyperformed at each of the shutter speeds of 1/100 of a second and 1/500of a second.

When the fluorescent lamp is lit by the alternating current having therepetition frequency of 50 Hz, the period of the light emission is 1/100of a second. When the fluorescent lamp is lit by the alternating currenthaving the repetition frequency of 60 Hz, the period of the lightemission is 1/120 of a second. On the other hand, the period ofphotography in a video camera is 1/60 of a second. Since the repetitionfrequency of light emission from a fluorescent lamp driven at 60 Hz is120 Hz, the integrated values in each type of photography performedunder light from a fluorescent lamp driven at 60 Hz are identical valuesat all times. By contrast, when photography is performed under lightfrom a fluorescent a lamp (light emission at 100 Hz) driven at 50 Hz,the integrated values differ (compare A₁, A₂ and A₃ or B₁, B₂ and B₃).This causes flickering.

Since the least common multiple of 1/60 and 1/100 is 1/20, theintegrated values will be the same every 1/20 of a second, i.e., everythree fields, even if photography is performed under a fluorescent lampdriven at 50 Hz. Flickering is thus prevented. Accordingly, theintegrated values A₁ and A₄ obtained every three fields will be equal orthe integrated values B₁ and B₄ obtained every three fields will beequal. However, the amount of light produced when a fluorescent lamp isdischarged from right to left differs from that produced when thefluorescent lamp is discharged from left to right. Consequently, theintegrated values will be equal every six fields and flickering will beprevented. In other words, the integrated values A₁ and A₇ will be equaland so will the integrated values B₁ and B₇.

In the video camera illustrated in FIG. 10, photography at the highshutter speed is performed one time every number of fields which is amultiple of six (every six fields, every 12 fields or every 18 fields,etc.). As a result, the integrated values of the video signals at eachhigh-speed photography timing will be the same and flickering can beprevented.

Fourth Embodiment

FIG. 15, which is for describing a fourth embodiment of the invention,is a block diagram illustrating the electrical configuration of a videocamera according to this embodiment. FIG. 16 is a graph illustrating thelevel of the video signal versus the brightness of a subject whenphotography is performed using the video camera shown in FIG. 15. Thegraph also illustrates the prevailing F number and a change in theamplification factor of the automatic gain control circuit 6 containedin the video camera. FIGS. 3a and 3b illustrating the recording formatsof the video camera are used in this embodiment as well.

The video camera includes the mode setting button 16 which makes itpossible to set the movie photography mode, the interval photographymode and the sports photography mode. As set forth earlier, the moviephotography mode is the ordinary photography mode in which a subject isphotographed continuously at a shutter speed of 1/60 of a second at alltimes. The interval photography mode is a mode in which a subject isphotographed continuously over a prescribed plurality of fields at ashutter speed of 1/60 of a second, with photography being performedperiodically at a high shutter speed (e.g., 1/250 of a second) in justone field (or one frame) among these plurality of fields. The sportsphotography mode is a mode in which a subject is photographedcontinuously at a high shutter speed at all times.

A signal representing the mode set by the mode setting button 16 isapplied to a system controller 220. On the basis of the entered modesetting signal, the system controller 220 outputs a shutter controlsignal to control the shutter control circuit 12, whereby photographyconforming to each mode is carried out. In the description that follows,a case will be discussed in which the interval photography mode has beenset by the mode setting switch 16.

The video camera is provided with a Hall device 211 and sensing circuit212 in order to sense whether the diaphragm has been opened fully. Thearrangement is such that the Hall voltage of the Hall device 211 variesin response to the diaphragm 3 being opened fully. The change in theHall voltage of the Hall device 211 is sensed by the sensing circuit212, whereby it is sensed that the diaphragm 3 is opened fully. Theoutput signal of the sensing circuit 212 indicating that the diaphragm 3is in the fully open state is sent from the circuit 212 to a switchcircuit 221 as a switch-changeover control signal.

A light image representing the image of a subject formed by the imagepick-up lens 2 is acted upon by the diaphragm 3 controlled by thediaphragm control circuit 11, whereby the image of the subject is formedon the CCD 4.

In the interval photography mode, an electronic shutter operation isperformed in the CCD 4 under the control of the shutter control circuit12 in such a manner that the sequence comprising the continuous exposureover a prescribed plurality of times at the ordinary shutter speed of1/60 of a second and the single exposure at the high shutter speed of1/250 of a second is repeated. This operation is illustrated in FIGS. 3aand 3b, in which the hatched portions indicate fields in whichphotography is performed at the high shutter speed and the otherportions indicate fields in which photography is performed at theordinary shutter speed. FIG. 3a depicts field recording and FIG. 3bframe recording. In the field mode, photography is performed at the highshutter speed one time in 16 fields. In the case of frame recording,photography is carried out at the-high shutter speed with regard to twosuccessive fields in photography performed 16 times. It goes withoutsaying that readout of the video signal from the CCD 4 is executed every1/60 of second, just as in an ordinary video camera, without relation tothe value of shutter speed.

When the illumination of the subject is low, the shutter speed isadjusted by the shutter control circuit 12 in such a manner that theoutput signal of the automatic gain control circuit 6 is maintained at aconstant level in order to obtain a reproduced image having a suitablebrightness.

As will be described later, a PI signal is superposed on the videosignal obtained by photography at the ordinary shutter speed, this videosignal being among those outputted by the CCD 4. The manner in which thePI signal is inserted also is shown in FIGS. 3a and 3b.

The video signal outputted by the CCD 4 is applied to the automatic gaincontrol circuit 6 and an averaging circuit 216 via the CDS (correlateddouble-sampling circuit) 5.

The averaging circuit 216 outputs the average level of one field of thevideo signal and is realized by an integrating circuit, by way ofexample. The averaging circuit 216 and an averaging circuit 230,described later, are controlled by a system controller 220 so as tocalculate the average level of the first video signal obtained byphotography at the ordinary shutter speed.

A voltage representing the average value outputted by the averagingcircuit 216 is applied to comparators 217A and 217B. The comparator 217Ais set to 80 mV as a first threshold value V₁. When the voltage thatenters from the averaging circuit 216 is less than 80 mV, the comparator217A provides the system controller 220 with a signal indicative of thisfact. The comparator 217B is set to 40 mV as a second threshold value V₂that is lower than the first threshold voltage V₁. When the voltage thatenters from the averaging circuit 216 is less than 40 mV, the comparator217b provides the system controller 220 with a signal indicative of thisfact.

The automatic gain control circuit 6 amplifies the entering video signalusing an amplification factor of 6 dB or 18.4 dB based upon the gaincontrol signal provided by the system controller 220. The automatic gaincontrol circuit 6 uses the amplification factor of 6 dB to amplify thefirst video signal obtained at the ordinary shutter speed, uses theamplification factor of 18.4 dB to amplify the second video signalobtained at the high shutter speed and performs an adjustment in such amanner that the average levels of the two amplified video signals willbecome approximately equal.

The video signals whose levels have thus been adjusted by the automaticgain control circuit 6 are applied to the signal processing circuit 7for the image sensing system. The signal processing circuit 7 subjectsthe video signals to processing for adjusting the color balance of thesesignals and performing a gamma correction, and generates a luminancesignal and color-difference signals. The signals obtained are applied tothe combining circuit 8.

The luminance signal generated by the signal processing circuit 7 forthe image sensing system is applied to the averaging circuit 230 aswell.

The averaging circuit 230 averages the luminance signal of the currentlyentering field, provides a differential amplifier circuit 219 with asignal representing the average level and provides a flicker detectingcircuit 240 with a signal representing the average level of theluminance signal of the current field and a signal representing theaverage level of the luminance signal of the field immediately precedingthe current field.

A differential output representing the difference between the outputlevel of the averaging circuit 230 and a predetermined suitablereference level is obtained by the differential amplifier circuit 219.The output voltage of the differential amplifier circuit 219 is appliedto the diaphragm control circuit 11 via a switch circuit 221 until thediaphragm 3 is opened fully. As a result, the opening/closing of thediaphragm 3 is controlled in such a manner that the output video signalof the CDS 5 will attain a fixed level in conformity with the shutterspeed, e.g., 100 mV in the case of the first video signal obtained atthe ordinary shutter speed and 24 mV in case of the second video signalobtained at the high shutter speed.

On the basis of the signal representing the average level of theluminance signal of the currently entering field and the signalrepresenting the average level of the luminance signal of theimmediately preceding field, the flicker detecting circuit 240 detectswhether flicker caused by fluorescent lighting, for example, iscontained in the current video signal. When flicker is detected, thecircuit 240 provides the system controller 220 with a signal to thiseffect, and the shutter control circuit 12 is controlled in such amanner that the shutter speed in case of both the high shutter speed andordinary shutter speed will become 1/100 of a second. The reason forthis will be described later.

The video camera further includes the PI signal generating circuit 20A.The latter is provided with the horizontal synchronizing signal HD, thevertical synchronizing signal VD and the clock signal CK from the SSG(synchronizing signal generating circuit ) 13. 0n the basis of theseinput signals, the PI signal generating circuit 20A generates the PIsignal, the information signal representing print information and theinterval timing pulses that decide the period of photography at the highshutter speed. The interval timing pulses are applied to the systemcontroller 220 and the PI signal is applied to the combining circuit 8.The circuit 20A has the construction shown in FIG. 12.

The combining circuit 8 superposes the PI signal outputted by the PIsignal generating circuit 20A on the video signals (at least theluminance signal) outputted by the signal processing circuit 7 for theimage sensing system.

An example of the PI signal is shown in FIG. 13 already described.

The PI signal illustrated in FIG. 13 is inserted in an initial intervalIT of a vertical blanking interval associated with the video signalobtained by performing photography at the ordinary shutter speed of 1/60of a second. The PI signal is not inserted in a vertical blankinginterval associated with the video signal obtained by performingphotography at the high shutter speed.

The vertical blanking interval associated with the video signalpreferably is a vertical blanking signal that appears immediately aheadof this video signal.

The PI signal is outputted by the PI signal generating circuit 20A at atiming at which it will be superposed upon the video signal between the17th and 18th horizontal synchronizing signals in the vertical blankinginterval, as shown in FIGS. 4a and 4b already described.

The video signal outputted by the combining circuit 8 is applied to thesignal processing circuit 9 for the recording system. The video signalis subjected to recording processing such as pre-emphasis and frequencymodulation processing by the recording processing circuit 9, after whichthe processed video signal is recorded on a video tape by the recordingplayback head 10.

The video camera shown in FIG. 15 can perform reproduction processing aswell and includes the signal processing circuit 17 for the playbacksystem. This circuit is identical with that described earlier inconnection with the first embodiment.

Operation of the video camera in conformity with the illumination of thesubject will now be described with particular reference to FIG. 16. Inthis operation also the interval photography mode is set, the highshutter speed is set to 1/250 of a second as a first high shutter speed,and the ordinary shutter speed is set to 1/60 of a second.

When the illumination of the subject is 1,000˜100,000 1×and the subjectis in shade or sunshine, the video signal obtained at the high shutterspeed (1/250 of a second) is amplified at the amplification factor of 18dB and the video signal obtained at the ordinary shutter speed (1/60 ofa second) is amplified at the amplification factor of 6 dB. As a result,the average level of the video signal obtained by photography at thehigh shutter speed and the average level of the video signal obtained byphotography at the ordinary shutter speed become approximately equal.

The switch circuit 221 is connected to the side of a b terminal so thatthe diaphragm 3 is controlled by the control circuit 11 in such a mannerthat the average level of the video signal outputted by the CDS 5 isheld at 24 mV with regard to the second video signal obtained byphotography at the high shutter speed and at 100 mV with regard to thefirst video signal obtained by photography at the ordinary shutterspeed.

Next, assume that the subject is inside a room and that flickering offluorescent lighting or the like has been detected by the flickerdetection circuit 240. Further, assume that the fluorescent lamp isbeing fired by an AC power supply having a commercial power-supplyfrequency of 50 Hz, as is the case in the Kanto district of Japan.

When flicker is detected, either the shutter speed that was the highspeed (1/250 of second) or the shutter speed that was the ordinary speed(1/60 of second) is set to the shutter speed of 1/100 of a second andthe subject is photographed. Since there is no distinction between thehigh shutter speed and the ordinary shutter speed, the automatic gaincontrol circuit 6 always performs amplification at the amplificationfactor of 6 dB at all times. The AC power-supply frequency of the Kantodistrict is 50 Hz, the period thereof is 1/50 of a second and theshutter speed is set to 1/100 of a second, which is the AC power-supplyperiod of 1/50 of a second multiplied by a factor of 1/2 . Consequently,as will be described below, it is possible to prevent flickering of thereproduced image caused by flicker ascribable to the fluorescentlighting or the like. Further, the AC power-supply frequency of theKansai district of Japan is 60 Hz. Therefore, when flicker is detectedin a video camera used primarily in the Kansai district, the shutterspeed is set to 1/120 of a second, which is the AC power-supply periodof 1/60 of a second multiplied by a factor of 1/2.

Even if flicker is detected and the shutter speed is set to 1/100 of asecond, the shutter speed is higher than the ordinary shutter speed of1/60 of a second and is suited to still reproduction. This means thatthe processing for superposing the PI signal is not executed at all withregard to the video signal.

A case will now be considered in which a subject located in a livingroom is photographed.

As the illumination of a subject diminishes, the diaphragm 3 isgradually opened based upon the output of differential amplifier circuit219 in such a manner that the average level of the output video signalfrom the CDS 5 will attain a constant level (100 mV or 24 mV) independence of the shutter speed. When the illumination of the subjectbecomes too low, the average level of the output video signal from theCDS 5 can no longer be held at the constant level conforming to theshutter speed even if the diaphragm 3 opened fully. In such a case, thefollowing operation is carried out:

The fact that the diaphragm 3 has been opened is sensed by the Halldevice 211 and sensing circuit 212. When the diaphragm 3 is opened, thesignal from the sensor indicative of this fact is applied to the switchcircuit 221, which is connected to the side of the a terminal. Owing tothe connection of the switch circuit 221 to the a terminal, thedifferential output of the differential amplifier circuit 219 is appliedto an adder circuit 218.

The gain control signal outputted by the system controller 220 and thedifferential output of the differential amplifier circuit 219 are addedby the adder circuit 218, and the resulting sum is applied to theautomatic gain control circuit 6 as a new gain control circuit. Thedifferential output of the differential amplifier circuit 219 is appliedto the adder circuit 218 irrespective of photography at the ordinaryshutter speed and photography at the high shutter speed. Accordingly,the amplification factor of 6 dB at the time of the ordinary shutterspeed and the amplification factor of 18.4 dB at the time of the highshutter speed are both enlarged. As a result, the average level of theoutput video signal from the automatic gain control circuit 6 will beheld substantially at a fixed level even if the illumination of thesubject changes.

Assume that the subject is in a comparatively dark location in a livingroom.

Since the diaphragm 3 will already be open, the lower the illuminationof the subject, the lower the average level of the output video signalof the CDS 5 will be, regardless of whether the video signal is oneobtained by photography at the ordinary shutter speed or one obtained byphotography at the high shutter speed.

When the average level of the video signal obtained at the ordinaryshutter speed falls below the first threshold level V₁, this is sensedby the comparator 217A, whose output signal indicative of this fact isapplied to the system controller 220. When this occurs, the shuttercontrol circuit 12 is controlled in such a manner that the first highshutter speed of 1/250 of a second will become a second high shutterspeed of 1/120 of a second that is lower than the first shutter speed of1/250 of a second but higher than the ordinary shutter speed of 1/60 ofa second, as illustrated at point B in FIG. 16.

The exposure time is lengthened by changing over the first high shutterspeed to the second high shutter speed. As a consequence, the level ofthe second video signal outputted by the CCD 4 also rises and the levelof the video signal outputted by the AGC 6 can be held at a fixed level.

Operation is as follows in a case where the subject is in a very darklocation and is photographed.

Assume that the level of the video signal outputted by the CDS 5 fallsfurther for both the first video signal and the second video signal, andthat the average level of the first video signal attains the secondthreshold value V2, as indicated at point C. When the average level ofthe first video signal attains the second threshold value V2, a signalindicative of this fact is outputted by the comparator 217B and entersthe system controller 220.

In response to the input from the comparator 217B, the system controller220 controls the shutter control circuit 12 in such a manner that thesecond high shutter speed of 1/120 of a second becomes the ordinaryshutter speed of 1/60 of a second. In this case, the high shutter speedand the ordinary shutter speed are no longer distinguishable from eachother. Photography is performed at the ordinary shutter speed at alltimes and there is no image obtained by photography at a shutter speedhigher than the ordinary shutter speed. As a consequence, the videosignal prevailing at this time is not suited to still playback. The PIsignal, therefore, is superposed upon all vertical blanking intervals ofthe video signal.

Further, if the subject is in a location even darker than that mentionedabove, the average value of the output video signal of the automaticgain control circuit 6 can no longer be maintained at the fixed leveleven by the shutter speed adjustment and the amplification processingthat is performed by the automatic gain control circuit 6. The averagelevel begins to decline at point A in FIG. 16.

Flicker detection processing will now be described.

FIG. 17 shows the electrical configuration of the averaging circuit 230and flicker detecting circuit 240, and FIG. 18 is a time chart showinginput and output signals of each circuit illustrated in FIG. 17. Theaveraging circuit 216 of FIG. 15 also has a construction substantiallythe same as that of the circuit 230 shown in FIG. 17.

The luminance signal produced by the signal processing circuit 7 for theimage sensing system is applied to gate circuits 232, 233 via a buffercircuit 231. The gate circuit 233 is controlled by a window signal WIND1outputted by the system controller 220, and the gate circuit 232 iscontrolled by a window signal WIND2 outputted by the system controller220.

The window signal WIND1 is outputted by the system controller 220 at atiming at which one field of the video signal obtained by photography atthe high shutter speed is extracted, and the window signal WIND2 isoutputted by the system controller 220 at a timing at which the fieldnext to the field of the video signal obtained by photography at thehigh shutter speed is extracted. The window signal WIND1 need notnecessarily be outputted in the field of the video signal resulting fromphotography at the high shutter speed.

The video signals that pass through the gate circuits 232 and 233 areapplied to integrating circuits 234 and 235, respectively.

The integrating circuit 234 comprises a capacitor C₄ and an FET F₄. Thesystem controller 220 applies a reset signal RST2 to the integratingcircuit 234 before the window signal WIND2 is outputted, therebyresetting the integrating circuit 234 (discharging the electric chargein the capacitor C4 through the FET F₄).

The integrating circuit 235 comprises a capacitor C₅ and an FET F₅. Thesystem controller 220 applies a reset signal RST2 to the integratingcircuit 235 before the window signal WIND1 is outputted, therebyresetting the integrating circuit 235 (discharging the electric chargein the capacitor C₅ through the FET F₅).

By applying the reset signal RST1 to the integrating circuit 235, theelectric charge in the capacitor C₅ is cleared and the electric chargeof the video signal obtained by photography at the high shutter speedaccumulates in the capacitor C₅. By applying the reset signal RST2 tothe integrating circuit 234, the electric charge in the capacitor C₄ iscleared and the electric charge of the video signal obtained byphotography at the ordinary shutter speed accumulates in the capacitorC₄.

The output of the integrating circuit 235 is applied to asample-and-hold circuit 239 via a buffer amplifier circuit 237, and theoutput of the integrating circuit 234 is applied to a sample-and-holdcircuit 238 via a buffer amplifier circuit 236.

The sample-and-hold circuit 239 comprises a FET F₉ and a capacitor C₉,and the sample-and-hold circuit 238 comprises a FET F₈ and a capacitorC₈. A sample-and-hold pulse SH is applied to the sample-and-holdcircuits 238 and 239 at a timing corresponding to the beginning of thefield that follows the field in which the window signal WIND2 isoutputted. As a result, the signals inputted to the circuits 238, 239are held.

The output of the sample-and-hold circuit 238 is applied to a bufferamplifier circuit 241 and a differential amplifier circuit 242. Theoutput of the buffer amplifier circuit 241 is a signal indicating theaveraged level of the first video signal (obtained at the ordinaryshutter speed).

The output of the sample-and-hold circuit 239 is applied to thedifferential amplifier circuit 242. The latter detects the differencebetween the average level of the video signal obtained by photography atthe high shutter speed and the average level of the video signal(obtained at the ordinary shutter speed) of the field following thevideo signal obtained by photography at the high shutter speed. Theoutput of the differential amplifier circuit 242 is applied to anabsolute-value circuit 243, whereby the absolute value of this signal isobtained.

When the subject is under flickering illumination as when a fluorescentlamp or the like is used for illumination, the luminance of the subjectfluctuates in conformity with the flickering and therefore brightnessdiffers from one picture to the next. In other words, the average levelsof two successive fields of the video signal differ. Accordingly, bycomparing the average levels of two fields of the video signalrepresenting successive images, as set forth above, it can be determinedwhether flickering will appear in the reproduced image.

The output of the absolute-value circuit 243 is applied to thecomparator 244. The latter compares the difference between the averagelevels of the two video signals with a threshold value E₀ and outputs aflicker-detection signal if the difference between the average levels isgreater than the threshold value. The flicker-detection signal isapplied to the system controller 220, as described above.

The processing for generating and superposing the PI signal is identicalwith that of the third embodiment.

The period of photography based upon the high shutter speed preferablyis in the range of 16 to 60 fields. The reason for this is that ifphotography at the high shutter speed is performed one time in 16fields, images played back in the form of a movie will not look unusual.And if photography at the high shutter speed is performed one time in 60fields, i.e., in one second, good photo opportunities will not be lost.

In the above-described embodiment, if the interval photography mode hasbeen set, photography is performed at the high shutter speed of 1/250 ofa second one time in 16 fields, and photography is performed at theordinary shutter speed of 1/60 of a second in the other fields, when thesubject is outdoors in shadow or sunlight or even when the subject isindoors but in a comparatively bright location such as an office. Thefirst video signal is amplified at the amplification factor of 6 dB andthe second video signal is amplified at the amplification factor of 18.4dB in such a manner that the average level of the first video signalobtained by photography at the ordinary shutter speed and the averagelevel of the second video signal obtained by photography at the highshutter speed become approximately equal. The difference between theseamplification factors is 12.4 dB.

When photography is performed at the ordinary shutter speed of 1/60 of asecond, this is not suited to still playback and the PI signal issuperposed upon the video signal for this reason. When photography isperformed at the high shutter speed of 1/250 of a second, this is suitedto still playback and therefore the PI signal is not superposed upon thevideo signal. By detecting whether or not the PI signal is present atthe time of playback, the second video signal suited to still playbackcan be extracted.

When flicker is detected, the shutter speeds of both 1/250 of a secondand 1/60 of a second are both set to 1/100 of a second to prevent thereproduced image from being affected by flickering ascribable to lightfrom a fluorescent lamp or the like.

The opening/closing of the diaphragm is controlled in dependence uponthe illumination of the subject in such a manner that the average levelof the video signal outputted by the CDS 5 will be 100 mV with respectto the first video signal and 24 mV with respect to the second videosignal.

When the diaphragm is opened in the dark circumstance, the output of theautomatic gain control circuit 6 declines. In order to maintain aconstant level, therefore, an adjustment is made in conformity with theillumination of the subject in such a manner that the amplificationfactor of the first video signal and the amplification factor of thesecond video signal will rise.

When the average level of the first video signal outputted by the CDS 5falls below the first threshold value V₁, the first high shutter speedof 1/250 of a second is changed to the second high shutter speed of1/120 of a second. When the average level of the first video signalfalls below the second threshold value V₂, the second high shutter speedof 1/120 of a second is changed to the ordinary shutter speed of 1/60 ofa second.

It is permissible to adopt an arrangement in which, when the averagelevel of the first video signal falls below the first threshold valueV1, the first high shutter speed of 1/250 of a second is changed to thesecond high shutter speed of 1/120 of a second and, when the averagelevel of the first video signal falls below the second threshold valueV₂, the second high shutter speed of 1/120 of a second is changed to athird high shutter speed of 1/100 of a second.

Furthermore, a third threshold value may be set that is lower than thesecond threshold value. In such case, the third high shutter speed of1/100 of a second would be changed to the ordinary shutter speed of 1/60of a second in response to the average level of the first video signalfalling below the third threshold value. When the third threshold valueis set, one more comparator to which the output signal of the averagingcircuit 216 is applied would be provided in order to detect that theaverage level of the first video signal has fallen below the thirdthreshold value.

Further, in the foregoing embodiment, the high shutter speed is changedover from 1/250 of a second to 1/120 of a second in response to theaverage level of the first video signal outputted by the CDS 5 fallingbelow the first threshold value V₁, and the high shutter speed ischanged over from 1/120 of a second to 1/60 of a second in response tothe average level of the first video signal falling below the secondthreshold value V₂. However, an arrangement may be adopted in which thehigh shutter speed is varied from 1/250 of a second to 1/60 of a secondcontinuously in dependence upon the average level of the first videosignal, or, in other words, in conformity with the illumination of thesubject.

In the foregoing embodiment, the opening/closing of the diaphragm iscontrolled in conformity with the illumination of the subject. However,the output of the automatic gain control circuit 6 can be held at aconstant level also by varying the amplification factors of theautomatic gain control circuit with respect to the first and secondvideo signals in conformity with the illumination of the subject withoutcontrolling the diaphragm.

Furthermore, in foregoing embodiment, the high shutter speed andordinary shutter speed are both changed to the shutter speed of 1/100 ofa second when flickering of light from a fluorescent lamp is detected.However, an arrangement may be adopted in which these shutter speeds arechanged to the ordinary shutter speed of 1/60 of a second when theillumination of the subject is low. Further, when flickering isdetected, the high shutter speed and ordinary shutter speed may both bechanged to the ordinary shutter speed of 1/60 of a second irrespectiveof the magnitude of the subject illumination. Since this would beunsuitable for still reproduction, the PI signal would be superposedupon the vertical blanking intervals of the video signal in all fields.

As many apparently widely different embodiments of the present inventioncan be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments thereof except as defined in the appended claims.

What is claimed is:
 1. A movie video camera comprising:shutterimplementing means for implementing a shutter having a high shutterspeed and a shutter having an ordinary shutter speed, the high shutterspeed being relatively higher than the ordinary shutter speed; modesetting means for selectively setting one of at least a moviephotography mode wherein a subject is photographed continuously at theordinary shutter speed and an interval photograph mode; shutter controlmeans for controlling said shutter implementing means in response to theselective setting of the interval photography mode, periodically foreach n times photography is performed, to automatically implement theshutter one time at the high shutter speed and to automaticallyimplement the shutter n-1 times at the ordinary shutter speed, wherein nis an integer; photographic means, responsive to selective setting ofthe interval photography mode, for outputting a first video signalrepresenting an image of a subject when the subject is exposed at theordinary shutter speed and for outputting a second video signalrepresenting an image of the subject when the subject is exposed at thehigh shutter speed; and recording means, responsive to selective settingof the interval photography mode, for recording the first and secondvideo signals, which are output from the photographic means, on arecording medium.
 2. The movie video camera according to claim 1,further comprising:print-inhibit signal superposing means, responsive toselective setting of the interval photography mode, for superposing aprint inhibit signal, which inhibits printing of an image represented bythe first video signal, in a vertical blanking interval associated withthe first video signal, which is obtained by exposure at the ordinaryshutter speed, among the first and second video signals outputted bysaid photographic means.
 3. The movie video camera according to claim 2,wherein said print-inhibit signal superposing means superposes the printinhibit signal between a 17th sequential horizontal synchronizing signaland an 18th sequential horizontal synchronizing signal in the verticalblanking interval of the first video signal.
 4. The movie video cameraaccording to claim 2, further comprising:a warning-signal superposingmeans for superposing a warning signal, which indicates that a secondvideo signal will be produced next by photography at the high shutterspeed, in the vertical blanking interval of the first video signaloutputted by said photographic means by photography at the ordinaryshutter speed, immediately preceding the photography performed at thehigh shutter speed.
 5. The movie video camera according to claim 2,further comprising:condition-signal superposing means for superposing aninformation signal, representing prevailing photographic information,when the second video signal is outputted or for superimposing printinformation useful when printing a picture represented by the secondvideo signal, said information signal being superposed in a verticalblanking interval associated with the second video signal, obtained byphotography under the high shutter speed, among the video signalsoutputted by said photographic means.
 6. The movie video cameraaccording to claim 1, further comprising:identification-signalsuperposing means for superposing an identification signal in a verticalblanking interval of a video signal outputted by the photographic means,said identification signal indicating whether the video signal is thefirst video signal or the second video signal.
 7. The movie video cameraaccording to claim 1, further comprising:an amplifier circuit foramplifying the video signals outputted by said photographic means; andgain control means for controlling gain of said amplifier circuit insuch a manner that the level of the second video signal obtained byexposure at the high shutter speed will become approximately equal tothe level of the first video signal obtained by exposure at the ordinaryshutter speed.
 8. The movie video camera according to claim 1, whereinsaid shutter control means controls said shutter implementing means suchthat photography at the high shutter speed is performed one timeperiodically in photography performed 16 or more times in succession andphotography at the ordinary shutter speed is performed at other times.9. The movie video camera according to claim 1, wherein said shuttercontrol means controls said shutter implementing means such thatphotography at the high shutter speed is performed one time periodicallyin photography performed more than 16 times and less than 60 times insuccession and photography at the ordinary shutter speed is performed atthe other times.
 10. A method of controlling a movie video camera,comprising the steps of:(a) selectively setting one of at least a moviephotography mode wherein a subject is photographed continuously at anordinary shutter speed and an interval photography mode; (b)automatically performing exposure one time at a high shutter speed andautomatically performing exposure n-1 times at the ordinary shutterspeed, periodically for each n times photography is performed, inresponse to the interval photography mode being selectively set in step(a), the high shutter speed being relatively higher than the ordinaryshutter speed and n being an integer; (c) obtaining a first video signalrepresenting an image of a subject when exposure is performed at theordinary shutter speed and obtaining a second video signal representingan image of the subject when exposure is performed at the high shutterspeed, in response to the interval photography mode being selectivelyset in step (a); and (d) recording the obtained first and second videosignals on a recording medium.
 11. The method according to claim 10,further comprising the step of:(e) superposing a print inhibit signal,which inhibits printing of an image represented by the first videosignal, in a vertical blanking interval of the first video signal, whichis obtained by exposure at the ordinary shutter speed among the videosignals obtained in step (c), in response to the selective setting ofthe interval photography mode in step (a).
 12. The method according toclaim 11, further comprising the step of:(f) superposing the printinhibit signal between a 17th sequential horizontal synchronizing signaland an 18th sequential horizontal synchronizing signal in the verticalblanking interval of the first video signal.
 13. The method according toclaim 10, further comprising the step of:(e) superposing a warningsignal, which indicates that a second video signal obtained in step (c)at the high shutter speed will be obtained next, in the verticalblanking interval of the first video signal obtained in step (c)outputted at the ordinary shutter speed, immediately preceding theexposure performed at the high shutter speed.
 14. The method accordingto claim 10, further comprising the step of:(e) superposing aninformation signal, representing prevailing photographic information,when the second video signal is obtained in step (c) or superimposingprint information useful when printing a picture represented by thesecond video signal, said information signal being superposed in avertical blanking interval associated with the second video signal,obtained under the high shutter speed, among the video signals obtainedin step (c).
 15. The method according to claim 10, further comprisingthe step of:(e) superposing an identification signal in a verticalblanking interval of a video signal obtained in step (c), saididentification signal indicating whether the video signal is the firstvideo signal or the second video signal.
 16. The method according toclaim 10, further comprising the step of: (e) amplifying the secondvideo signal in such a manner that the level of the second video signalobtained by exposure at the high shutter speed will become approximatelyequal to the level of the first video signal obtained by exposure at theordinary shutter speed.
 17. The method according to claim 10, furthercomprising the step of: (e) performing photography at the high shutterspeed one time periodically in photography performed 16 or more times insuccession and photography at the ordinary shutter speed at other times.18. The method according to claim 10, further comprising the step of:(e) performing photography at the high shutter speed one timeperiodically in photography performed more than 16 times and less than60 times in succession and photography at the ordinary shutter speed atother times.
 19. The movie video camera of claim 1, wherein the highshutter speed is 1/120 of a second.
 20. The movie video camera of claim1, wherein the high shutter speed is 1/250 of a second.
 21. The methodof claim 10, wherein the high shutter speed is 1/120 of a second. 22.The method of claim 10, wherein the high shutter speed is 1/250 of asecond.
 23. The movie video camera of claim 1, wherein the first andsecond video signals are recorded on a common single recording medium.24. The method of claim 10, wherein step (d) includes recording theobtained first and second video signals on a common single recordingmedium.
 25. The movie video camera of claim 1, wherein n times equals nframes.
 26. The movie video camera of claim 1, wherein n times equals nfields.
 27. The method of claim 10, wherein n times equals n fields. 28.The method of claim 10, wherein n times equals n frames.